Index: imaps-frontend/node_modules/immutable/dist/immutable.d.ts
===================================================================
--- imaps-frontend/node_modules/immutable/dist/immutable.d.ts	(revision 0c6b92add4cfaedcb91bcd37b45849f142f7d152)
+++ imaps-frontend/node_modules/immutable/dist/immutable.d.ts	(revision 0c6b92add4cfaedcb91bcd37b45849f142f7d152)
@@ -0,0 +1,6105 @@
+/** @ignore we should disable this rules, but let's activate it to enable eslint first */
+/* eslint-disable @typescript-eslint/no-explicit-any, @typescript-eslint/ban-types */
+/**
+ * Immutable data encourages pure functions (data-in, data-out) and lends itself
+ * to much simpler application development and enabling techniques from
+ * functional programming such as lazy evaluation.
+ *
+ * While designed to bring these powerful functional concepts to JavaScript, it
+ * presents an Object-Oriented API familiar to Javascript engineers and closely
+ * mirroring that of Array, Map, and Set. It is easy and efficient to convert to
+ * and from plain Javascript types.
+ *
+ * ## How to read these docs
+ *
+ * In order to better explain what kinds of values the Immutable.js API expects
+ * and produces, this documentation is presented in a statically typed dialect of
+ * JavaScript (like [Flow][] or [TypeScript][]). You *don't need* to use these
+ * type checking tools in order to use Immutable.js, however becoming familiar
+ * with their syntax will help you get a deeper understanding of this API.
+ *
+ * **A few examples and how to read them.**
+ *
+ * All methods describe the kinds of data they accept and the kinds of data
+ * they return. For example a function which accepts two numbers and returns
+ * a number would look like this:
+ *
+ * ```js
+ * sum(first: number, second: number): number
+ * ```
+ *
+ * Sometimes, methods can accept different kinds of data or return different
+ * kinds of data, and this is described with a *type variable*, which is
+ * typically in all-caps. For example, a function which always returns the same
+ * kind of data it was provided would look like this:
+ *
+ * ```js
+ * identity<T>(value: T): T
+ * ```
+ *
+ * Type variables are defined with classes and referred to in methods. For
+ * example, a class that holds onto a value for you might look like this:
+ *
+ * ```js
+ * class Box<T> {
+ *   constructor(value: T)
+ *   getValue(): T
+ * }
+ * ```
+ *
+ * In order to manipulate Immutable data, methods that we're used to affecting
+ * a Collection instead return a new Collection of the same type. The type
+ * `this` refers to the same kind of class. For example, a List which returns
+ * new Lists when you `push` a value onto it might look like:
+ *
+ * ```js
+ * class List<T> {
+ *   push(value: T): this
+ * }
+ * ```
+ *
+ * Many methods in Immutable.js accept values which implement the JavaScript
+ * [Iterable][] protocol, and might appear like `Iterable<string>` for something
+ * which represents sequence of strings. Typically in JavaScript we use plain
+ * Arrays (`[]`) when an Iterable is expected, but also all of the Immutable.js
+ * collections are iterable themselves!
+ *
+ * For example, to get a value deep within a structure of data, we might use
+ * `getIn` which expects an `Iterable` path:
+ *
+ * ```
+ * getIn(path: Iterable<string | number>): unknown
+ * ```
+ *
+ * To use this method, we could pass an array: `data.getIn([ "key", 2 ])`.
+ *
+ *
+ * Note: All examples are presented in the modern [ES2015][] version of
+ * JavaScript. Use tools like Babel to support older browsers.
+ *
+ * For example:
+ *
+ * ```js
+ * // ES2015
+ * const mappedFoo = foo.map(x => x * x);
+ * // ES5
+ * var mappedFoo = foo.map(function (x) { return x * x; });
+ * ```
+ *
+ * [ES2015]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/New_in_JavaScript/ECMAScript_6_support_in_Mozilla
+ * [TypeScript]: https://www.typescriptlang.org/
+ * [Flow]: https://flowtype.org/
+ * [Iterable]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols
+ */
+
+declare namespace Immutable {
+  /** @ignore */
+  type OnlyObject<T> = Extract<T, object>;
+
+  /** @ignore */
+  type ContainObject<T> = OnlyObject<T> extends object
+    ? OnlyObject<T> extends never
+      ? false
+      : true
+    : false;
+
+  /**
+   * @ignore
+   *
+   * Used to convert deeply all immutable types to a plain TS type.
+   * Using `unknown` on object instead of recursive call as we have a circular reference issue
+   */
+  export type DeepCopy<T> = T extends Record<infer R>
+    ? // convert Record to DeepCopy plain JS object
+      {
+        [key in keyof R]: ContainObject<R[key]> extends true ? unknown : R[key];
+      }
+    : T extends MapOf<infer R>
+    ? // convert MapOf to DeepCopy plain JS object
+      {
+        [key in keyof R]: ContainObject<R[key]> extends true ? unknown : R[key];
+      }
+    : T extends Collection.Keyed<infer KeyedKey, infer V>
+    ? // convert KeyedCollection to DeepCopy plain JS object
+      {
+        [key in KeyedKey extends string | number | symbol
+          ? KeyedKey
+          : string]: V extends object ? unknown : V;
+      }
+    : // convert IndexedCollection or Immutable.Set to DeepCopy plain JS array
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    T extends Collection<infer _, infer V>
+    ? Array<DeepCopy<V>>
+    : T extends string | number // Iterable scalar types : should be kept as is
+    ? T
+    : T extends Iterable<infer V> // Iterable are converted to plain JS array
+    ? Array<DeepCopy<V>>
+    : T extends object // plain JS object are converted deeply
+    ? {
+        [ObjectKey in keyof T]: ContainObject<T[ObjectKey]> extends true
+          ? unknown
+          : T[ObjectKey];
+      }
+    : // other case : should be kept as is
+      T;
+
+  /**
+   * Describes which item in a pair should be placed first when sorting
+   *
+   * @ignore
+   */
+  export enum PairSorting {
+    LeftThenRight = -1,
+    RightThenLeft = +1,
+  }
+
+  /**
+   * Function comparing two items of the same type. It can return:
+   *
+   * * a PairSorting value, to indicate whether the left-hand item or the right-hand item should be placed before the other
+   *
+   * * the traditional numeric return value - especially -1, 0, or 1
+   *
+   * @ignore
+   */
+  export type Comparator<T> = (left: T, right: T) => PairSorting | number;
+
+  /**
+   * Lists are ordered indexed dense collections, much like a JavaScript
+   * Array.
+   *
+   * Lists are immutable and fully persistent with O(log32 N) gets and sets,
+   * and O(1) push and pop.
+   *
+   * Lists implement Deque, with efficient addition and removal from both the
+   * end (`push`, `pop`) and beginning (`unshift`, `shift`).
+   *
+   * Unlike a JavaScript Array, there is no distinction between an
+   * "unset" index and an index set to `undefined`. `List#forEach` visits all
+   * indices from 0 to size, regardless of whether they were explicitly defined.
+   */
+  namespace List {
+    /**
+     * True if the provided value is a List
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { List } = require('immutable');
+     * List.isList([]); // false
+     * List.isList(List()); // true
+     * ```
+     */
+    function isList(maybeList: unknown): maybeList is List<unknown>;
+
+    /**
+     * Creates a new List containing `values`.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { List } = require('immutable');
+     * List.of(1, 2, 3, 4)
+     * // List [ 1, 2, 3, 4 ]
+     * ```
+     *
+     * Note: Values are not altered or converted in any way.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { List } = require('immutable');
+     * List.of({x:1}, 2, [3], 4)
+     * // List [ { x: 1 }, 2, [ 3 ], 4 ]
+     * ```
+     */
+    function of<T>(...values: Array<T>): List<T>;
+  }
+
+  /**
+   * Create a new immutable List containing the values of the provided
+   * collection-like.
+   *
+   * Note: `List` is a factory function and not a class, and does not use the
+   * `new` keyword during construction.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { List, Set } = require('immutable')
+   *
+   * const emptyList = List()
+   * // List []
+   *
+   * const plainArray = [ 1, 2, 3, 4 ]
+   * const listFromPlainArray = List(plainArray)
+   * // List [ 1, 2, 3, 4 ]
+   *
+   * const plainSet = Set([ 1, 2, 3, 4 ])
+   * const listFromPlainSet = List(plainSet)
+   * // List [ 1, 2, 3, 4 ]
+   *
+   * const arrayIterator = plainArray[Symbol.iterator]()
+   * const listFromCollectionArray = List(arrayIterator)
+   * // List [ 1, 2, 3, 4 ]
+   *
+   * listFromPlainArray.equals(listFromCollectionArray) // true
+   * listFromPlainSet.equals(listFromCollectionArray) // true
+   * listFromPlainSet.equals(listFromPlainArray) // true
+   * ```
+   */
+  function List<T>(collection?: Iterable<T> | ArrayLike<T>): List<T>;
+
+  interface List<T> extends Collection.Indexed<T> {
+    /**
+     * The number of items in this List.
+     */
+    readonly size: number;
+
+    // Persistent changes
+
+    /**
+     * Returns a new List which includes `value` at `index`. If `index` already
+     * exists in this List, it will be replaced.
+     *
+     * `index` may be a negative number, which indexes back from the end of the
+     * List. `v.set(-1, "value")` sets the last item in the List.
+     *
+     * If `index` larger than `size`, the returned List's `size` will be large
+     * enough to include the `index`.
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { List } = require('immutable');" }
+     * -->
+     * ```js
+     * const originalList = List([ 0 ]);
+     * // List [ 0 ]
+     * originalList.set(1, 1);
+     * // List [ 0, 1 ]
+     * originalList.set(0, 'overwritten');
+     * // List [ "overwritten" ]
+     * originalList.set(2, 2);
+     * // List [ 0, undefined, 2 ]
+     *
+     * List().set(50000, 'value').size;
+     * // 50001
+     * ```
+     *
+     * Note: `set` can be used in `withMutations`.
+     */
+    set(index: number, value: T): List<T>;
+
+    /**
+     * Returns a new List which excludes this `index` and with a size 1 less
+     * than this List. Values at indices above `index` are shifted down by 1 to
+     * fill the position.
+     *
+     * This is synonymous with `list.splice(index, 1)`.
+     *
+     * `index` may be a negative number, which indexes back from the end of the
+     * List. `v.delete(-1)` deletes the last item in the List.
+     *
+     * Note: `delete` cannot be safely used in IE8
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { List } = require('immutable');" }
+     * -->
+     * ```js
+     * List([ 0, 1, 2, 3, 4 ]).delete(0);
+     * // List [ 1, 2, 3, 4 ]
+     * ```
+     *
+     * Since `delete()` re-indexes values, it produces a complete copy, which
+     * has `O(N)` complexity.
+     *
+     * Note: `delete` *cannot* be used in `withMutations`.
+     *
+     * @alias remove
+     */
+    delete(index: number): List<T>;
+    remove(index: number): List<T>;
+
+    /**
+     * Returns a new List with `value` at `index` with a size 1 more than this
+     * List. Values at indices above `index` are shifted over by 1.
+     *
+     * This is synonymous with `list.splice(index, 0, value)`.
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { List } = require('immutable');" }
+     * -->
+     * ```js
+     * List([ 0, 1, 2, 3, 4 ]).insert(6, 5)
+     * // List [ 0, 1, 2, 3, 4, 5 ]
+     * ```
+     *
+     * Since `insert()` re-indexes values, it produces a complete copy, which
+     * has `O(N)` complexity.
+     *
+     * Note: `insert` *cannot* be used in `withMutations`.
+     */
+    insert(index: number, value: T): List<T>;
+
+    /**
+     * Returns a new List with 0 size and no values in constant time.
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { List } = require('immutable');" }
+     * -->
+     * ```js
+     * List([ 1, 2, 3, 4 ]).clear()
+     * // List []
+     * ```
+     *
+     * Note: `clear` can be used in `withMutations`.
+     */
+    clear(): List<T>;
+
+    /**
+     * Returns a new List with the provided `values` appended, starting at this
+     * List's `size`.
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { List } = require('immutable');" }
+     * -->
+     * ```js
+     * List([ 1, 2, 3, 4 ]).push(5)
+     * // List [ 1, 2, 3, 4, 5 ]
+     * ```
+     *
+     * Note: `push` can be used in `withMutations`.
+     */
+    push(...values: Array<T>): List<T>;
+
+    /**
+     * Returns a new List with a size ones less than this List, excluding
+     * the last index in this List.
+     *
+     * Note: this differs from `Array#pop` because it returns a new
+     * List rather than the removed value. Use `last()` to get the last value
+     * in this List.
+     *
+     * ```js
+     * List([ 1, 2, 3, 4 ]).pop()
+     * // List[ 1, 2, 3 ]
+     * ```
+     *
+     * Note: `pop` can be used in `withMutations`.
+     */
+    pop(): List<T>;
+
+    /**
+     * Returns a new List with the provided `values` prepended, shifting other
+     * values ahead to higher indices.
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { List } = require('immutable');" }
+     * -->
+     * ```js
+     * List([ 2, 3, 4]).unshift(1);
+     * // List [ 1, 2, 3, 4 ]
+     * ```
+     *
+     * Note: `unshift` can be used in `withMutations`.
+     */
+    unshift(...values: Array<T>): List<T>;
+
+    /**
+     * Returns a new List with a size ones less than this List, excluding
+     * the first index in this List, shifting all other values to a lower index.
+     *
+     * Note: this differs from `Array#shift` because it returns a new
+     * List rather than the removed value. Use `first()` to get the first
+     * value in this List.
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { List } = require('immutable');" }
+     * -->
+     * ```js
+     * List([ 0, 1, 2, 3, 4 ]).shift();
+     * // List [ 1, 2, 3, 4 ]
+     * ```
+     *
+     * Note: `shift` can be used in `withMutations`.
+     */
+    shift(): List<T>;
+
+    /**
+     * Returns a new List with an updated value at `index` with the return
+     * value of calling `updater` with the existing value, or `notSetValue` if
+     * `index` was not set. If called with a single argument, `updater` is
+     * called with the List itself.
+     *
+     * `index` may be a negative number, which indexes back from the end of the
+     * List. `v.update(-1)` updates the last item in the List.
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { List } = require('immutable');" }
+     * -->
+     * ```js
+     * const list = List([ 'a', 'b', 'c' ])
+     * const result = list.update(2, val => val.toUpperCase())
+     * // List [ "a", "b", "C" ]
+     * ```
+     *
+     * This can be very useful as a way to "chain" a normal function into a
+     * sequence of methods. RxJS calls this "let" and lodash calls it "thru".
+     *
+     * For example, to sum a List after mapping and filtering:
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { List } = require('immutable');" }
+     * -->
+     * ```js
+     * function sum(collection) {
+     *   return collection.reduce((sum, x) => sum + x, 0)
+     * }
+     *
+     * List([ 1, 2, 3 ])
+     *   .map(x => x + 1)
+     *   .filter(x => x % 2 === 0)
+     *   .update(sum)
+     * // 6
+     * ```
+     *
+     * Note: `update(index)` can be used in `withMutations`.
+     *
+     * @see `Map#update`
+     */
+    update(index: number, notSetValue: T, updater: (value: T) => T): this;
+    update(
+      index: number,
+      updater: (value: T | undefined) => T | undefined
+    ): this;
+    update<R>(updater: (value: this) => R): R;
+
+    /**
+     * Returns a new List with size `size`. If `size` is less than this
+     * List's size, the new List will exclude values at the higher indices.
+     * If `size` is greater than this List's size, the new List will have
+     * undefined values for the newly available indices.
+     *
+     * When building a new List and the final size is known up front, `setSize`
+     * used in conjunction with `withMutations` may result in the more
+     * performant construction.
+     */
+    setSize(size: number): List<T>;
+
+    // Deep persistent changes
+
+    /**
+     * Returns a new List having set `value` at this `keyPath`. If any keys in
+     * `keyPath` do not exist, a new immutable Map will be created at that key.
+     *
+     * Index numbers are used as keys to determine the path to follow in
+     * the List.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { List } = require('immutable')
+     * const list = List([ 0, 1, 2, List([ 3, 4 ])])
+     * list.setIn([3, 0], 999);
+     * // List [ 0, 1, 2, List [ 999, 4 ] ]
+     * ```
+     *
+     * Plain JavaScript Object or Arrays may be nested within an Immutable.js
+     * Collection, and setIn() can update those values as well, treating them
+     * immutably by creating new copies of those values with the changes applied.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { List } = require('immutable')
+     * const list = List([ 0, 1, 2, { plain: 'object' }])
+     * list.setIn([3, 'plain'], 'value');
+     * // List([ 0, 1, 2, { plain: 'value' }])
+     * ```
+     *
+     * Note: `setIn` can be used in `withMutations`.
+     */
+    setIn(keyPath: Iterable<unknown>, value: unknown): this;
+
+    /**
+     * Returns a new List having removed the value at this `keyPath`. If any
+     * keys in `keyPath` do not exist, no change will occur.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { List } = require('immutable')
+     * const list = List([ 0, 1, 2, List([ 3, 4 ])])
+     * list.deleteIn([3, 0]);
+     * // List [ 0, 1, 2, List [ 4 ] ]
+     * ```
+     *
+     * Plain JavaScript Object or Arrays may be nested within an Immutable.js
+     * Collection, and removeIn() can update those values as well, treating them
+     * immutably by creating new copies of those values with the changes applied.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { List } = require('immutable')
+     * const list = List([ 0, 1, 2, { plain: 'object' }])
+     * list.removeIn([3, 'plain']);
+     * // List([ 0, 1, 2, {}])
+     * ```
+     *
+     * Note: `deleteIn` *cannot* be safely used in `withMutations`.
+     *
+     * @alias removeIn
+     */
+    deleteIn(keyPath: Iterable<unknown>): this;
+    removeIn(keyPath: Iterable<unknown>): this;
+
+    /**
+     * Note: `updateIn` can be used in `withMutations`.
+     *
+     * @see `Map#updateIn`
+     */
+    updateIn(
+      keyPath: Iterable<unknown>,
+      notSetValue: unknown,
+      updater: (value: unknown) => unknown
+    ): this;
+    updateIn(
+      keyPath: Iterable<unknown>,
+      updater: (value: unknown) => unknown
+    ): this;
+
+    /**
+     * Note: `mergeIn` can be used in `withMutations`.
+     *
+     * @see `Map#mergeIn`
+     */
+    mergeIn(keyPath: Iterable<unknown>, ...collections: Array<unknown>): this;
+
+    /**
+     * Note: `mergeDeepIn` can be used in `withMutations`.
+     *
+     * @see `Map#mergeDeepIn`
+     */
+    mergeDeepIn(
+      keyPath: Iterable<unknown>,
+      ...collections: Array<unknown>
+    ): this;
+
+    // Transient changes
+
+    /**
+     * Note: Not all methods can be safely used on a mutable collection or within
+     * `withMutations`! Check the documentation for each method to see if it
+     * allows being used in `withMutations`.
+     *
+     * @see `Map#withMutations`
+     */
+    withMutations(mutator: (mutable: this) => unknown): this;
+
+    /**
+     * An alternative API for withMutations()
+     *
+     * Note: Not all methods can be safely used on a mutable collection or within
+     * `withMutations`! Check the documentation for each method to see if it
+     * allows being used in `withMutations`.
+     *
+     * @see `Map#asMutable`
+     */
+    asMutable(): this;
+
+    /**
+     * @see `Map#wasAltered`
+     */
+    wasAltered(): boolean;
+
+    /**
+     * @see `Map#asImmutable`
+     */
+    asImmutable(): this;
+
+    // Sequence algorithms
+
+    /**
+     * Returns a new List with other values or collections concatenated to this one.
+     *
+     * Note: `concat` can be used in `withMutations`.
+     *
+     * @alias merge
+     */
+    concat<C>(...valuesOrCollections: Array<Iterable<C> | C>): List<T | C>;
+    merge<C>(...collections: Array<Iterable<C>>): List<T | C>;
+
+    /**
+     * Returns a new List with values passed through a
+     * `mapper` function.
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { List } = require('immutable');" }
+     * -->
+     * ```js
+     * List([ 1, 2 ]).map(x => 10 * x)
+     * // List [ 10, 20 ]
+     * ```
+     */
+    map<M>(
+      mapper: (value: T, key: number, iter: this) => M,
+      context?: unknown
+    ): List<M>;
+
+    /**
+     * Flat-maps the List, returning a new List.
+     *
+     * Similar to `list.map(...).flatten(true)`.
+     */
+    flatMap<M>(
+      mapper: (value: T, key: number, iter: this) => Iterable<M>,
+      context?: unknown
+    ): List<M>;
+
+    /**
+     * Returns a new List with only the values for which the `predicate`
+     * function returns true.
+     *
+     * Note: `filter()` always returns a new instance, even if it results in
+     * not filtering out any values.
+     */
+    filter<F extends T>(
+      predicate: (value: T, index: number, iter: this) => value is F,
+      context?: unknown
+    ): List<F>;
+    filter(
+      predicate: (value: T, index: number, iter: this) => unknown,
+      context?: unknown
+    ): this;
+
+    /**
+     * Returns a new List with the values for which the `predicate`
+     * function returns false and another for which is returns true.
+     */
+    partition<F extends T, C>(
+      predicate: (this: C, value: T, index: number, iter: this) => value is F,
+      context?: C
+    ): [List<T>, List<F>];
+    partition<C>(
+      predicate: (this: C, value: T, index: number, iter: this) => unknown,
+      context?: C
+    ): [this, this];
+
+    /**
+     * Returns a List "zipped" with the provided collection.
+     *
+     * Like `zipWith`, but using the default `zipper`: creating an `Array`.
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { List } = require('immutable');" }
+     * -->
+     * ```js
+     * const a = List([ 1, 2, 3 ]);
+     * const b = List([ 4, 5, 6 ]);
+     * const c = a.zip(b); // List [ [ 1, 4 ], [ 2, 5 ], [ 3, 6 ] ]
+     * ```
+     */
+    zip<U>(other: Collection<unknown, U>): List<[T, U]>;
+    zip<U, V>(
+      other: Collection<unknown, U>,
+      other2: Collection<unknown, V>
+    ): List<[T, U, V]>;
+    zip(...collections: Array<Collection<unknown, unknown>>): List<unknown>;
+
+    /**
+     * Returns a List "zipped" with the provided collections.
+     *
+     * Unlike `zip`, `zipAll` continues zipping until the longest collection is
+     * exhausted. Missing values from shorter collections are filled with `undefined`.
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { List } = require('immutable');" }
+     * -->
+     * ```js
+     * const a = List([ 1, 2 ]);
+     * const b = List([ 3, 4, 5 ]);
+     * const c = a.zipAll(b); // List [ [ 1, 3 ], [ 2, 4 ], [ undefined, 5 ] ]
+     * ```
+     *
+     * Note: Since zipAll will return a collection as large as the largest
+     * input, some results may contain undefined values. TypeScript cannot
+     * account for these without cases (as of v2.5).
+     */
+    zipAll<U>(other: Collection<unknown, U>): List<[T, U]>;
+    zipAll<U, V>(
+      other: Collection<unknown, U>,
+      other2: Collection<unknown, V>
+    ): List<[T, U, V]>;
+    zipAll(...collections: Array<Collection<unknown, unknown>>): List<unknown>;
+
+    /**
+     * Returns a List "zipped" with the provided collections by using a
+     * custom `zipper` function.
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { List } = require('immutable');" }
+     * -->
+     * ```js
+     * const a = List([ 1, 2, 3 ]);
+     * const b = List([ 4, 5, 6 ]);
+     * const c = a.zipWith((a, b) => a + b, b);
+     * // List [ 5, 7, 9 ]
+     * ```
+     */
+    zipWith<U, Z>(
+      zipper: (value: T, otherValue: U) => Z,
+      otherCollection: Collection<unknown, U>
+    ): List<Z>;
+    zipWith<U, V, Z>(
+      zipper: (value: T, otherValue: U, thirdValue: V) => Z,
+      otherCollection: Collection<unknown, U>,
+      thirdCollection: Collection<unknown, V>
+    ): List<Z>;
+    zipWith<Z>(
+      zipper: (...values: Array<unknown>) => Z,
+      ...collections: Array<Collection<unknown, unknown>>
+    ): List<Z>;
+  }
+
+  /**
+   * Immutable Map is an unordered Collection.Keyed of (key, value) pairs with
+   * `O(log32 N)` gets and `O(log32 N)` persistent sets.
+   *
+   * Iteration order of a Map is undefined, however is stable. Multiple
+   * iterations of the same Map will iterate in the same order.
+   *
+   * Map's keys can be of any type, and use `Immutable.is` to determine key
+   * equality. This allows the use of any value (including NaN) as a key.
+   *
+   * Because `Immutable.is` returns equality based on value semantics, and
+   * Immutable collections are treated as values, any Immutable collection may
+   * be used as a key.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { Map, List } = require('immutable');
+   * Map().set(List([ 1 ]), 'listofone').get(List([ 1 ]));
+   * // 'listofone'
+   * ```
+   *
+   * Any JavaScript object may be used as a key, however strict identity is used
+   * to evaluate key equality. Two similar looking objects will represent two
+   * different keys.
+   *
+   * Implemented by a hash-array mapped trie.
+   */
+  namespace Map {
+    /**
+     * True if the provided value is a Map
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map } = require('immutable')
+     * Map.isMap({}) // false
+     * Map.isMap(Map()) // true
+     * ```
+     */
+    function isMap(maybeMap: unknown): maybeMap is Map<unknown, unknown>;
+  }
+
+  /**
+   * Creates a new Immutable Map.
+   *
+   * Created with the same key value pairs as the provided Collection.Keyed or
+   * JavaScript Object or expects a Collection of [K, V] tuple entries.
+   *
+   * Note: `Map` is a factory function and not a class, and does not use the
+   * `new` keyword during construction.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { Map } = require('immutable')
+   * Map({ key: "value" })
+   * Map([ [ "key", "value" ] ])
+   * ```
+   *
+   * Keep in mind, when using JS objects to construct Immutable Maps, that
+   * JavaScript Object properties are always strings, even if written in a
+   * quote-less shorthand, while Immutable Maps accept keys of any type.
+   *
+   * <!-- runkit:activate
+   *      { "preamble": "const { Map } = require('immutable');" }
+   * -->
+   * ```js
+   * let obj = { 1: "one" }
+   * Object.keys(obj) // [ "1" ]
+   * assert.equal(obj["1"], obj[1]) // "one" === "one"
+   *
+   * let map = Map(obj)
+   * assert.notEqual(map.get("1"), map.get(1)) // "one" !== undefined
+   * ```
+   *
+   * Property access for JavaScript Objects first converts the key to a string,
+   * but since Immutable Map keys can be of any type the argument to `get()` is
+   * not altered.
+   */
+  function Map<K, V>(collection?: Iterable<[K, V]>): Map<K, V>;
+  function Map<R extends { [key in string | number | symbol]: unknown }>(
+    obj: R
+  ): MapOf<R>;
+  function Map<V>(obj: { [key: string]: V }): Map<string, V>;
+  function Map<K extends string | symbol, V>(obj: { [P in K]?: V }): Map<K, V>;
+
+  /**
+   * Represent a Map constructed by an object
+   *
+   * @ignore
+   */
+  interface MapOf<R extends { [key in string | number | symbol]: unknown }>
+    extends Map<keyof R, R[keyof R]> {
+    /**
+     * Returns the value associated with the provided key, or notSetValue if
+     * the Collection does not contain this key.
+     *
+     * Note: it is possible a key may be associated with an `undefined` value,
+     * so if `notSetValue` is not provided and this method returns `undefined`,
+     * that does not guarantee the key was not found.
+     */
+    get<K extends keyof R>(key: K, notSetValue?: unknown): R[K];
+    get<NSV>(key: any, notSetValue: NSV): NSV;
+
+    // TODO `<const P extends ...>` can be used after dropping support for TypeScript 4.x
+    // reference: https://www.typescriptlang.org/docs/handbook/release-notes/typescript-5-0.html#const-type-parameters
+    // after this change, `as const` assertions can be remove from the type tests
+    getIn<P extends ReadonlyArray<string | number | symbol>>(
+      searchKeyPath: [...P],
+      notSetValue?: unknown
+    ): RetrievePath<R, P>;
+
+    set<K extends keyof R>(key: K, value: R[K]): this;
+
+    update(updater: (value: this) => this): this;
+    update<K extends keyof R>(key: K, updater: (value: R[K]) => R[K]): this;
+    update<K extends keyof R, NSV extends R[K]>(
+      key: K,
+      notSetValue: NSV,
+      updater: (value: R[K]) => R[K]
+    ): this;
+
+    // Possible best type is MapOf<Omit<R, K>> but Omit seems to broke other function calls
+    // and generate recursion error with other methods (update, merge, etc.) until those functions are defined in MapOf
+    delete<K extends keyof R>(
+      key: K
+    ): Extract<R[K], undefined> extends never ? never : this;
+    remove<K extends keyof R>(
+      key: K
+    ): Extract<R[K], undefined> extends never ? never : this;
+
+    toJS(): { [K in keyof R]: DeepCopy<R[K]> };
+
+    toJSON(): { [K in keyof R]: R[K] };
+  }
+
+  // Loosely based off of this work.
+  // https://github.com/immutable-js/immutable-js/issues/1462#issuecomment-584123268
+
+  /** @ignore */
+  type GetMapType<S> = S extends MapOf<infer T> ? T : S;
+
+  /** @ignore */
+  type Head<T extends ReadonlyArray<any>> = T extends [
+    infer H,
+    ...Array<unknown>
+  ]
+    ? H
+    : never;
+
+  /** @ignore */
+  type Tail<T extends ReadonlyArray<any>> = T extends [unknown, ...infer I]
+    ? I
+    : Array<never>;
+
+  /** @ignore */
+  type RetrievePathReducer<
+    T,
+    C,
+    L extends ReadonlyArray<any>
+  > = C extends keyof GetMapType<T>
+    ? L extends []
+      ? GetMapType<T>[C]
+      : RetrievePathReducer<GetMapType<T>[C], Head<L>, Tail<L>>
+    : never;
+
+  /** @ignore */
+  type RetrievePath<
+    R,
+    P extends ReadonlyArray<string | number | symbol>
+  > = P extends [] ? P : RetrievePathReducer<R, Head<P>, Tail<P>>;
+
+  interface Map<K, V> extends Collection.Keyed<K, V> {
+    /**
+     * The number of entries in this Map.
+     */
+    readonly size: number;
+
+    // Persistent changes
+
+    /**
+     * Returns a new Map also containing the new key, value pair. If an equivalent
+     * key already exists in this Map, it will be replaced.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map } = require('immutable')
+     * const originalMap = Map()
+     * const newerMap = originalMap.set('key', 'value')
+     * const newestMap = newerMap.set('key', 'newer value')
+     *
+     * originalMap
+     * // Map {}
+     * newerMap
+     * // Map { "key": "value" }
+     * newestMap
+     * // Map { "key": "newer value" }
+     * ```
+     *
+     * Note: `set` can be used in `withMutations`.
+     */
+    set(key: K, value: V): this;
+
+    /**
+     * Returns a new Map which excludes this `key`.
+     *
+     * Note: `delete` cannot be safely used in IE8, but is provided to mirror
+     * the ES6 collection API.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map } = require('immutable')
+     * const originalMap = Map({
+     *   key: 'value',
+     *   otherKey: 'other value'
+     * })
+     * // Map { "key": "value", "otherKey": "other value" }
+     * originalMap.delete('otherKey')
+     * // Map { "key": "value" }
+     * ```
+     *
+     * Note: `delete` can be used in `withMutations`.
+     *
+     * @alias remove
+     */
+    delete(key: K): this;
+    remove(key: K): this;
+
+    /**
+     * Returns a new Map which excludes the provided `keys`.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map } = require('immutable')
+     * const names = Map({ a: "Aaron", b: "Barry", c: "Connor" })
+     * names.deleteAll([ 'a', 'c' ])
+     * // Map { "b": "Barry" }
+     * ```
+     *
+     * Note: `deleteAll` can be used in `withMutations`.
+     *
+     * @alias removeAll
+     */
+    deleteAll(keys: Iterable<K>): this;
+    removeAll(keys: Iterable<K>): this;
+
+    /**
+     * Returns a new Map containing no keys or values.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map } = require('immutable')
+     * Map({ key: 'value' }).clear()
+     * // Map {}
+     * ```
+     *
+     * Note: `clear` can be used in `withMutations`.
+     */
+    clear(): this;
+
+    /**
+     * Returns a new Map having updated the value at this `key` with the return
+     * value of calling `updater` with the existing value.
+     *
+     * Similar to: `map.set(key, updater(map.get(key)))`.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map } = require('immutable')
+     * const aMap = Map({ key: 'value' })
+     * const newMap = aMap.update('key', value => value + value)
+     * // Map { "key": "valuevalue" }
+     * ```
+     *
+     * This is most commonly used to call methods on collections within a
+     * structure of data. For example, in order to `.push()` onto a nested `List`,
+     * `update` and `push` can be used together:
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { Map, List } = require('immutable');" }
+     * -->
+     * ```js
+     * const aMap = Map({ nestedList: List([ 1, 2, 3 ]) })
+     * const newMap = aMap.update('nestedList', list => list.push(4))
+     * // Map { "nestedList": List [ 1, 2, 3, 4 ] }
+     * ```
+     *
+     * When a `notSetValue` is provided, it is provided to the `updater`
+     * function when the value at the key does not exist in the Map.
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { Map } = require('immutable');" }
+     * -->
+     * ```js
+     * const aMap = Map({ key: 'value' })
+     * const newMap = aMap.update('noKey', 'no value', value => value + value)
+     * // Map { "key": "value", "noKey": "no valueno value" }
+     * ```
+     *
+     * However, if the `updater` function returns the same value it was called
+     * with, then no change will occur. This is still true if `notSetValue`
+     * is provided.
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { Map } = require('immutable');" }
+     * -->
+     * ```js
+     * const aMap = Map({ apples: 10 })
+     * const newMap = aMap.update('oranges', 0, val => val)
+     * // Map { "apples": 10 }
+     * assert.strictEqual(newMap, map);
+     * ```
+     *
+     * For code using ES2015 or later, using `notSetValue` is discourged in
+     * favor of function parameter default values. This helps to avoid any
+     * potential confusion with identify functions as described above.
+     *
+     * The previous example behaves differently when written with default values:
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { Map } = require('immutable');" }
+     * -->
+     * ```js
+     * const aMap = Map({ apples: 10 })
+     * const newMap = aMap.update('oranges', (val = 0) => val)
+     * // Map { "apples": 10, "oranges": 0 }
+     * ```
+     *
+     * If no key is provided, then the `updater` function return value is
+     * returned as well.
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { Map } = require('immutable');" }
+     * -->
+     * ```js
+     * const aMap = Map({ key: 'value' })
+     * const result = aMap.update(aMap => aMap.get('key'))
+     * // "value"
+     * ```
+     *
+     * This can be very useful as a way to "chain" a normal function into a
+     * sequence of methods. RxJS calls this "let" and lodash calls it "thru".
+     *
+     * For example, to sum the values in a Map
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { Map } = require('immutable');" }
+     * -->
+     * ```js
+     * function sum(collection) {
+     *   return collection.reduce((sum, x) => sum + x, 0)
+     * }
+     *
+     * Map({ x: 1, y: 2, z: 3 })
+     *   .map(x => x + 1)
+     *   .filter(x => x % 2 === 0)
+     *   .update(sum)
+     * // 6
+     * ```
+     *
+     * Note: `update(key)` can be used in `withMutations`.
+     */
+    update(key: K, notSetValue: V, updater: (value: V) => V): this;
+    update(key: K, updater: (value: V | undefined) => V | undefined): this;
+    update<R>(updater: (value: this) => R): R;
+
+    /**
+     * Returns a new Map resulting from merging the provided Collections
+     * (or JS objects) into this Map. In other words, this takes each entry of
+     * each collection and sets it on this Map.
+     *
+     * Note: Values provided to `merge` are shallowly converted before being
+     * merged. No nested values are altered.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map } = require('immutable')
+     * const one = Map({ a: 10, b: 20, c: 30 })
+     * const two = Map({ b: 40, a: 50, d: 60 })
+     * one.merge(two) // Map { "a": 50, "b": 40, "c": 30, "d": 60 }
+     * two.merge(one) // Map { "b": 20, "a": 10, "d": 60, "c": 30 }
+     * ```
+     *
+     * Note: `merge` can be used in `withMutations`.
+     *
+     * @alias concat
+     */
+    merge<KC, VC>(
+      ...collections: Array<Iterable<[KC, VC]>>
+    ): Map<K | KC, Exclude<V, VC> | VC>;
+    merge<C>(
+      ...collections: Array<{ [key: string]: C }>
+    ): Map<K | string, Exclude<V, C> | C>;
+
+    concat<KC, VC>(
+      ...collections: Array<Iterable<[KC, VC]>>
+    ): Map<K | KC, Exclude<V, VC> | VC>;
+    concat<C>(
+      ...collections: Array<{ [key: string]: C }>
+    ): Map<K | string, Exclude<V, C> | C>;
+
+    /**
+     * Like `merge()`, `mergeWith()` returns a new Map resulting from merging
+     * the provided Collections (or JS objects) into this Map, but uses the
+     * `merger` function for dealing with conflicts.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map } = require('immutable')
+     * const one = Map({ a: 10, b: 20, c: 30 })
+     * const two = Map({ b: 40, a: 50, d: 60 })
+     * one.mergeWith((oldVal, newVal) => oldVal / newVal, two)
+     * // { "a": 0.2, "b": 0.5, "c": 30, "d": 60 }
+     * two.mergeWith((oldVal, newVal) => oldVal / newVal, one)
+     * // { "b": 2, "a": 5, "d": 60, "c": 30 }
+     * ```
+     *
+     * Note: `mergeWith` can be used in `withMutations`.
+     */
+    mergeWith<KC, VC, VCC>(
+      merger: (oldVal: V, newVal: VC, key: K) => VCC,
+      ...collections: Array<Iterable<[KC, VC]>>
+    ): Map<K | KC, V | VC | VCC>;
+    mergeWith<C, CC>(
+      merger: (oldVal: V, newVal: C, key: string) => CC,
+      ...collections: Array<{ [key: string]: C }>
+    ): Map<K | string, V | C | CC>;
+
+    /**
+     * Like `merge()`, but when two compatible collections are encountered with
+     * the same key, it merges them as well, recursing deeply through the nested
+     * data. Two collections are considered to be compatible (and thus will be
+     * merged together) if they both fall into one of three categories: keyed
+     * (e.g., `Map`s, `Record`s, and objects), indexed (e.g., `List`s and
+     * arrays), or set-like (e.g., `Set`s). If they fall into separate
+     * categories, `mergeDeep` will replace the existing collection with the
+     * collection being merged in. This behavior can be customized by using
+     * `mergeDeepWith()`.
+     *
+     * Note: Indexed and set-like collections are merged using
+     * `concat()`/`union()` and therefore do not recurse.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map } = require('immutable')
+     * const one = Map({ a: Map({ x: 10, y: 10 }), b: Map({ x: 20, y: 50 }) })
+     * const two = Map({ a: Map({ x: 2 }), b: Map({ y: 5 }), c: Map({ z: 3 }) })
+     * one.mergeDeep(two)
+     * // Map {
+     * //   "a": Map { "x": 2, "y": 10 },
+     * //   "b": Map { "x": 20, "y": 5 },
+     * //   "c": Map { "z": 3 }
+     * // }
+     * ```
+     *
+     * Note: `mergeDeep` can be used in `withMutations`.
+     */
+    mergeDeep<KC, VC>(
+      ...collections: Array<Iterable<[KC, VC]>>
+    ): Map<K | KC, V | VC>;
+    mergeDeep<C>(
+      ...collections: Array<{ [key: string]: C }>
+    ): Map<K | string, V | C>;
+
+    /**
+     * Like `mergeDeep()`, but when two non-collections or incompatible
+     * collections are encountered at the same key, it uses the `merger`
+     * function to determine the resulting value. Collections are considered
+     * incompatible if they fall into separate categories between keyed,
+     * indexed, and set-like.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map } = require('immutable')
+     * const one = Map({ a: Map({ x: 10, y: 10 }), b: Map({ x: 20, y: 50 }) })
+     * const two = Map({ a: Map({ x: 2 }), b: Map({ y: 5 }), c: Map({ z: 3 }) })
+     * one.mergeDeepWith((oldVal, newVal) => oldVal / newVal, two)
+     * // Map {
+     * //   "a": Map { "x": 5, "y": 10 },
+     * //   "b": Map { "x": 20, "y": 10 },
+     * //   "c": Map { "z": 3 }
+     * // }
+     * ```
+     *
+     * Note: `mergeDeepWith` can be used in `withMutations`.
+     */
+    mergeDeepWith(
+      merger: (oldVal: unknown, newVal: unknown, key: unknown) => unknown,
+      ...collections: Array<Iterable<[K, V]> | { [key: string]: V }>
+    ): this;
+
+    // Deep persistent changes
+
+    /**
+     * Returns a new Map having set `value` at this `keyPath`. If any keys in
+     * `keyPath` do not exist, a new immutable Map will be created at that key.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map } = require('immutable')
+     * const originalMap = Map({
+     *   subObject: Map({
+     *     subKey: 'subvalue',
+     *     subSubObject: Map({
+     *       subSubKey: 'subSubValue'
+     *     })
+     *   })
+     * })
+     *
+     * const newMap = originalMap.setIn(['subObject', 'subKey'], 'ha ha!')
+     * // Map {
+     * //   "subObject": Map {
+     * //     "subKey": "ha ha!",
+     * //     "subSubObject": Map { "subSubKey": "subSubValue" }
+     * //   }
+     * // }
+     *
+     * const newerMap = originalMap.setIn(
+     *   ['subObject', 'subSubObject', 'subSubKey'],
+     *   'ha ha ha!'
+     * )
+     * // Map {
+     * //   "subObject": Map {
+     * //     "subKey": "subvalue",
+     * //     "subSubObject": Map { "subSubKey": "ha ha ha!" }
+     * //   }
+     * // }
+     * ```
+     *
+     * Plain JavaScript Object or Arrays may be nested within an Immutable.js
+     * Collection, and setIn() can update those values as well, treating them
+     * immutably by creating new copies of those values with the changes applied.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map } = require('immutable')
+     * const originalMap = Map({
+     *   subObject: {
+     *     subKey: 'subvalue',
+     *     subSubObject: {
+     *       subSubKey: 'subSubValue'
+     *     }
+     *   }
+     * })
+     *
+     * originalMap.setIn(['subObject', 'subKey'], 'ha ha!')
+     * // Map {
+     * //   "subObject": {
+     * //     subKey: "ha ha!",
+     * //     subSubObject: { subSubKey: "subSubValue" }
+     * //   }
+     * // }
+     * ```
+     *
+     * If any key in the path exists but cannot be updated (such as a primitive
+     * like number or a custom Object like Date), an error will be thrown.
+     *
+     * Note: `setIn` can be used in `withMutations`.
+     */
+    setIn(keyPath: Iterable<unknown>, value: unknown): this;
+
+    /**
+     * Returns a new Map having removed the value at this `keyPath`. If any keys
+     * in `keyPath` do not exist, no change will occur.
+     *
+     * Note: `deleteIn` can be used in `withMutations`.
+     *
+     * @alias removeIn
+     */
+    deleteIn(keyPath: Iterable<unknown>): this;
+    removeIn(keyPath: Iterable<unknown>): this;
+
+    /**
+     * Returns a new Map having applied the `updater` to the entry found at the
+     * keyPath.
+     *
+     * This is most commonly used to call methods on collections nested within a
+     * structure of data. For example, in order to `.push()` onto a nested `List`,
+     * `updateIn` and `push` can be used together:
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map, List } = require('immutable')
+     * const map = Map({ inMap: Map({ inList: List([ 1, 2, 3 ]) }) })
+     * const newMap = map.updateIn(['inMap', 'inList'], list => list.push(4))
+     * // Map { "inMap": Map { "inList": List [ 1, 2, 3, 4 ] } }
+     * ```
+     *
+     * If any keys in `keyPath` do not exist, new Immutable `Map`s will
+     * be created at those keys. If the `keyPath` does not already contain a
+     * value, the `updater` function will be called with `notSetValue`, if
+     * provided, otherwise `undefined`.
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { Map } = require('immutable')" }
+     * -->
+     * ```js
+     * const map = Map({ a: Map({ b: Map({ c: 10 }) }) })
+     * const newMap = map.updateIn(['a', 'b', 'c'], val => val * 2)
+     * // Map { "a": Map { "b": Map { "c": 20 } } }
+     * ```
+     *
+     * If the `updater` function returns the same value it was called with, then
+     * no change will occur. This is still true if `notSetValue` is provided.
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { Map } = require('immutable')" }
+     * -->
+     * ```js
+     * const map = Map({ a: Map({ b: Map({ c: 10 }) }) })
+     * const newMap = map.updateIn(['a', 'b', 'x'], 100, val => val)
+     * // Map { "a": Map { "b": Map { "c": 10 } } }
+     * assert.strictEqual(newMap, aMap)
+     * ```
+     *
+     * For code using ES2015 or later, using `notSetValue` is discourged in
+     * favor of function parameter default values. This helps to avoid any
+     * potential confusion with identify functions as described above.
+     *
+     * The previous example behaves differently when written with default values:
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { Map } = require('immutable')" }
+     * -->
+     * ```js
+     * const map = Map({ a: Map({ b: Map({ c: 10 }) }) })
+     * const newMap = map.updateIn(['a', 'b', 'x'], (val = 100) => val)
+     * // Map { "a": Map { "b": Map { "c": 10, "x": 100 } } }
+     * ```
+     *
+     * Plain JavaScript Object or Arrays may be nested within an Immutable.js
+     * Collection, and updateIn() can update those values as well, treating them
+     * immutably by creating new copies of those values with the changes applied.
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { Map } = require('immutable')" }
+     * -->
+     * ```js
+     * const map = Map({ a: { b: { c: 10 } } })
+     * const newMap = map.updateIn(['a', 'b', 'c'], val => val * 2)
+     * // Map { "a": { b: { c: 20 } } }
+     * ```
+     *
+     * If any key in the path exists but cannot be updated (such as a primitive
+     * like number or a custom Object like Date), an error will be thrown.
+     *
+     * Note: `updateIn` can be used in `withMutations`.
+     */
+    updateIn(
+      keyPath: Iterable<unknown>,
+      notSetValue: unknown,
+      updater: (value: unknown) => unknown
+    ): this;
+    updateIn(
+      keyPath: Iterable<unknown>,
+      updater: (value: unknown) => unknown
+    ): this;
+
+    /**
+     * A combination of `updateIn` and `merge`, returning a new Map, but
+     * performing the merge at a point arrived at by following the keyPath.
+     * In other words, these two lines are equivalent:
+     *
+     * ```js
+     * map.updateIn(['a', 'b', 'c'], abc => abc.merge(y))
+     * map.mergeIn(['a', 'b', 'c'], y)
+     * ```
+     *
+     * Note: `mergeIn` can be used in `withMutations`.
+     */
+    mergeIn(keyPath: Iterable<unknown>, ...collections: Array<unknown>): this;
+
+    /**
+     * A combination of `updateIn` and `mergeDeep`, returning a new Map, but
+     * performing the deep merge at a point arrived at by following the keyPath.
+     * In other words, these two lines are equivalent:
+     *
+     * ```js
+     * map.updateIn(['a', 'b', 'c'], abc => abc.mergeDeep(y))
+     * map.mergeDeepIn(['a', 'b', 'c'], y)
+     * ```
+     *
+     * Note: `mergeDeepIn` can be used in `withMutations`.
+     */
+    mergeDeepIn(
+      keyPath: Iterable<unknown>,
+      ...collections: Array<unknown>
+    ): this;
+
+    // Transient changes
+
+    /**
+     * Every time you call one of the above functions, a new immutable Map is
+     * created. If a pure function calls a number of these to produce a final
+     * return value, then a penalty on performance and memory has been paid by
+     * creating all of the intermediate immutable Maps.
+     *
+     * If you need to apply a series of mutations to produce a new immutable
+     * Map, `withMutations()` creates a temporary mutable copy of the Map which
+     * can apply mutations in a highly performant manner. In fact, this is
+     * exactly how complex mutations like `merge` are done.
+     *
+     * As an example, this results in the creation of 2, not 4, new Maps:
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map } = require('immutable')
+     * const map1 = Map()
+     * const map2 = map1.withMutations(map => {
+     *   map.set('a', 1).set('b', 2).set('c', 3)
+     * })
+     * assert.equal(map1.size, 0)
+     * assert.equal(map2.size, 3)
+     * ```
+     *
+     * Note: Not all methods can be used on a mutable collection or within
+     * `withMutations`! Read the documentation for each method to see if it
+     * is safe to use in `withMutations`.
+     */
+    withMutations(mutator: (mutable: this) => unknown): this;
+
+    /**
+     * Another way to avoid creation of intermediate Immutable maps is to create
+     * a mutable copy of this collection. Mutable copies *always* return `this`,
+     * and thus shouldn't be used for equality. Your function should never return
+     * a mutable copy of a collection, only use it internally to create a new
+     * collection.
+     *
+     * If possible, use `withMutations` to work with temporary mutable copies as
+     * it provides an easier to use API and considers many common optimizations.
+     *
+     * Note: if the collection is already mutable, `asMutable` returns itself.
+     *
+     * Note: Not all methods can be used on a mutable collection or within
+     * `withMutations`! Read the documentation for each method to see if it
+     * is safe to use in `withMutations`.
+     *
+     * @see `Map#asImmutable`
+     */
+    asMutable(): this;
+
+    /**
+     * Returns true if this is a mutable copy (see `asMutable()`) and mutative
+     * alterations have been applied.
+     *
+     * @see `Map#asMutable`
+     */
+    wasAltered(): boolean;
+
+    /**
+     * The yin to `asMutable`'s yang. Because it applies to mutable collections,
+     * this operation is *mutable* and may return itself (though may not
+     * return itself, i.e. if the result is an empty collection). Once
+     * performed, the original mutable copy must no longer be mutated since it
+     * may be the immutable result.
+     *
+     * If possible, use `withMutations` to work with temporary mutable copies as
+     * it provides an easier to use API and considers many common optimizations.
+     *
+     * @see `Map#asMutable`
+     */
+    asImmutable(): this;
+
+    // Sequence algorithms
+
+    /**
+     * Returns a new Map with values passed through a
+     * `mapper` function.
+     *
+     *     Map({ a: 1, b: 2 }).map(x => 10 * x)
+     *     // Map { a: 10, b: 20 }
+     */
+    map<M>(
+      mapper: (value: V, key: K, iter: this) => M,
+      context?: unknown
+    ): Map<K, M>;
+
+    /**
+     * @see Collection.Keyed.mapKeys
+     */
+    mapKeys<M>(
+      mapper: (key: K, value: V, iter: this) => M,
+      context?: unknown
+    ): Map<M, V>;
+
+    /**
+     * @see Collection.Keyed.mapEntries
+     */
+    mapEntries<KM, VM>(
+      mapper: (
+        entry: [K, V],
+        index: number,
+        iter: this
+      ) => [KM, VM] | undefined,
+      context?: unknown
+    ): Map<KM, VM>;
+
+    /**
+     * Flat-maps the Map, returning a new Map.
+     *
+     * Similar to `data.map(...).flatten(true)`.
+     */
+    flatMap<KM, VM>(
+      mapper: (value: V, key: K, iter: this) => Iterable<[KM, VM]>,
+      context?: unknown
+    ): Map<KM, VM>;
+
+    /**
+     * Returns a new Map with only the entries for which the `predicate`
+     * function returns true.
+     *
+     * Note: `filter()` always returns a new instance, even if it results in
+     * not filtering out any values.
+     */
+    filter<F extends V>(
+      predicate: (value: V, key: K, iter: this) => value is F,
+      context?: unknown
+    ): Map<K, F>;
+    filter(
+      predicate: (value: V, key: K, iter: this) => unknown,
+      context?: unknown
+    ): this;
+
+    /**
+     * Returns a new Map with the values for which the `predicate`
+     * function returns false and another for which is returns true.
+     */
+    partition<F extends V, C>(
+      predicate: (this: C, value: V, key: K, iter: this) => value is F,
+      context?: C
+    ): [Map<K, V>, Map<K, F>];
+    partition<C>(
+      predicate: (this: C, value: V, key: K, iter: this) => unknown,
+      context?: C
+    ): [this, this];
+
+    /**
+     * @see Collection.Keyed.flip
+     */
+    flip(): Map<V, K>;
+
+    /**
+     * Returns an OrderedMap of the same type which includes the same entries,
+     * stably sorted by using a `comparator`.
+     *
+     * If a `comparator` is not provided, a default comparator uses `<` and `>`.
+     *
+     * `comparator(valueA, valueB)`:
+     *
+     *   * Returns `0` if the elements should not be swapped.
+     *   * Returns `-1` (or any negative number) if `valueA` comes before `valueB`
+     *   * Returns `1` (or any positive number) if `valueA` comes after `valueB`
+     *   * Alternatively, can return a value of the `PairSorting` enum type
+     *   * Is pure, i.e. it must always return the same value for the same pair
+     *     of values.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map } = require('immutable')
+     * Map({ "c": 3, "a": 1, "b": 2 }).sort((a, b) => {
+     *   if (a < b) { return -1; }
+     *   if (a > b) { return 1; }
+     *   if (a === b) { return 0; }
+     * });
+     * // OrderedMap { "a": 1, "b": 2, "c": 3 }
+     * ```
+     *
+     * Note: `sort()` Always returns a new instance, even if the original was
+     * already sorted.
+     *
+     * Note: This is always an eager operation.
+     */
+    sort(comparator?: Comparator<V>): this & OrderedMap<K, V>;
+
+    /**
+     * Like `sort`, but also accepts a `comparatorValueMapper` which allows for
+     * sorting by more sophisticated means:
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map } = require('immutable')
+     * const beattles = Map({
+     *   John: { name: "Lennon" },
+     *   Paul: { name: "McCartney" },
+     *   George: { name: "Harrison" },
+     *   Ringo: { name: "Starr" },
+     * });
+     * beattles.sortBy(member => member.name);
+     * ```
+     *
+     * Note: `sortBy()` Always returns a new instance, even if the original was
+     * already sorted.
+     *
+     * Note: This is always an eager operation.
+     */
+    sortBy<C>(
+      comparatorValueMapper: (value: V, key: K, iter: this) => C,
+      comparator?: (valueA: C, valueB: C) => number
+    ): this & OrderedMap<K, V>;
+  }
+
+  /**
+   * A type of Map that has the additional guarantee that the iteration order of
+   * entries will be the order in which they were set().
+   *
+   * The iteration behavior of OrderedMap is the same as native ES6 Map and
+   * JavaScript Object.
+   *
+   * Note that `OrderedMap` are more expensive than non-ordered `Map` and may
+   * consume more memory. `OrderedMap#set` is amortized O(log32 N), but not
+   * stable.
+   */
+  namespace OrderedMap {
+    /**
+     * True if the provided value is an OrderedMap.
+     */
+    function isOrderedMap(
+      maybeOrderedMap: unknown
+    ): maybeOrderedMap is OrderedMap<unknown, unknown>;
+  }
+
+  /**
+   * Creates a new Immutable OrderedMap.
+   *
+   * Created with the same key value pairs as the provided Collection.Keyed or
+   * JavaScript Object or expects a Collection of [K, V] tuple entries.
+   *
+   * The iteration order of key-value pairs provided to this constructor will
+   * be preserved in the OrderedMap.
+   *
+   *     let newOrderedMap = OrderedMap({key: "value"})
+   *     let newOrderedMap = OrderedMap([["key", "value"]])
+   *
+   * Note: `OrderedMap` is a factory function and not a class, and does not use
+   * the `new` keyword during construction.
+   */
+  function OrderedMap<K, V>(collection?: Iterable<[K, V]>): OrderedMap<K, V>;
+  function OrderedMap<V>(obj: { [key: string]: V }): OrderedMap<string, V>;
+
+  interface OrderedMap<K, V> extends Map<K, V> {
+    /**
+     * The number of entries in this OrderedMap.
+     */
+    readonly size: number;
+
+    /**
+     * Returns a new OrderedMap also containing the new key, value pair. If an
+     * equivalent key already exists in this OrderedMap, it will be replaced
+     * while maintaining the existing order.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { OrderedMap } = require('immutable')
+     * const originalMap = OrderedMap({a:1, b:1, c:1})
+     * const updatedMap = originalMap.set('b', 2)
+     *
+     * originalMap
+     * // OrderedMap {a: 1, b: 1, c: 1}
+     * updatedMap
+     * // OrderedMap {a: 1, b: 2, c: 1}
+     * ```
+     *
+     * Note: `set` can be used in `withMutations`.
+     */
+    set(key: K, value: V): this;
+
+    /**
+     * Returns a new OrderedMap resulting from merging the provided Collections
+     * (or JS objects) into this OrderedMap. In other words, this takes each
+     * entry of each collection and sets it on this OrderedMap.
+     *
+     * Note: Values provided to `merge` are shallowly converted before being
+     * merged. No nested values are altered.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { OrderedMap } = require('immutable')
+     * const one = OrderedMap({ a: 10, b: 20, c: 30 })
+     * const two = OrderedMap({ b: 40, a: 50, d: 60 })
+     * one.merge(two) // OrderedMap { "a": 50, "b": 40, "c": 30, "d": 60 }
+     * two.merge(one) // OrderedMap { "b": 20, "a": 10, "d": 60, "c": 30 }
+     * ```
+     *
+     * Note: `merge` can be used in `withMutations`.
+     *
+     * @alias concat
+     */
+    merge<KC, VC>(
+      ...collections: Array<Iterable<[KC, VC]>>
+    ): OrderedMap<K | KC, Exclude<V, VC> | VC>;
+    merge<C>(
+      ...collections: Array<{ [key: string]: C }>
+    ): OrderedMap<K | string, Exclude<V, C> | C>;
+
+    concat<KC, VC>(
+      ...collections: Array<Iterable<[KC, VC]>>
+    ): OrderedMap<K | KC, Exclude<V, VC> | VC>;
+    concat<C>(
+      ...collections: Array<{ [key: string]: C }>
+    ): OrderedMap<K | string, Exclude<V, C> | C>;
+
+    mergeWith<KC, VC, VCC>(
+      merger: (oldVal: V, newVal: VC, key: K) => VCC,
+      ...collections: Array<Iterable<[KC, VC]>>
+    ): OrderedMap<K | KC, V | VC | VCC>;
+    mergeWith<C, CC>(
+      merger: (oldVal: V, newVal: C, key: string) => CC,
+      ...collections: Array<{ [key: string]: C }>
+    ): OrderedMap<K | string, V | C | CC>;
+
+    mergeDeep<KC, VC>(
+      ...collections: Array<Iterable<[KC, VC]>>
+    ): OrderedMap<K | KC, V | VC>;
+    mergeDeep<C>(
+      ...collections: Array<{ [key: string]: C }>
+    ): OrderedMap<K | string, V | C>;
+
+    // Sequence algorithms
+
+    /**
+     * Returns a new OrderedMap with values passed through a
+     * `mapper` function.
+     *
+     *     OrderedMap({ a: 1, b: 2 }).map(x => 10 * x)
+     *     // OrderedMap { "a": 10, "b": 20 }
+     *
+     * Note: `map()` always returns a new instance, even if it produced the same
+     * value at every step.
+     */
+    map<M>(
+      mapper: (value: V, key: K, iter: this) => M,
+      context?: unknown
+    ): OrderedMap<K, M>;
+
+    /**
+     * @see Collection.Keyed.mapKeys
+     */
+    mapKeys<M>(
+      mapper: (key: K, value: V, iter: this) => M,
+      context?: unknown
+    ): OrderedMap<M, V>;
+
+    /**
+     * @see Collection.Keyed.mapEntries
+     */
+    mapEntries<KM, VM>(
+      mapper: (
+        entry: [K, V],
+        index: number,
+        iter: this
+      ) => [KM, VM] | undefined,
+      context?: unknown
+    ): OrderedMap<KM, VM>;
+
+    /**
+     * Flat-maps the OrderedMap, returning a new OrderedMap.
+     *
+     * Similar to `data.map(...).flatten(true)`.
+     */
+    flatMap<KM, VM>(
+      mapper: (value: V, key: K, iter: this) => Iterable<[KM, VM]>,
+      context?: unknown
+    ): OrderedMap<KM, VM>;
+
+    /**
+     * Returns a new OrderedMap with only the entries for which the `predicate`
+     * function returns true.
+     *
+     * Note: `filter()` always returns a new instance, even if it results in
+     * not filtering out any values.
+     */
+    filter<F extends V>(
+      predicate: (value: V, key: K, iter: this) => value is F,
+      context?: unknown
+    ): OrderedMap<K, F>;
+    filter(
+      predicate: (value: V, key: K, iter: this) => unknown,
+      context?: unknown
+    ): this;
+
+    /**
+     * Returns a new OrderedMap with the values for which the `predicate`
+     * function returns false and another for which is returns true.
+     */
+    partition<F extends V, C>(
+      predicate: (this: C, value: V, key: K, iter: this) => value is F,
+      context?: C
+    ): [OrderedMap<K, V>, OrderedMap<K, F>];
+    partition<C>(
+      predicate: (this: C, value: V, key: K, iter: this) => unknown,
+      context?: C
+    ): [this, this];
+
+    /**
+     * @see Collection.Keyed.flip
+     */
+    flip(): OrderedMap<V, K>;
+  }
+
+  /**
+   * A Collection of unique values with `O(log32 N)` adds and has.
+   *
+   * When iterating a Set, the entries will be (value, value) pairs. Iteration
+   * order of a Set is undefined, however is stable. Multiple iterations of the
+   * same Set will iterate in the same order.
+   *
+   * Set values, like Map keys, may be of any type. Equality is determined using
+   * `Immutable.is`, enabling Sets to uniquely include other Immutable
+   * collections, custom value types, and NaN.
+   */
+  namespace Set {
+    /**
+     * True if the provided value is a Set
+     */
+    function isSet(maybeSet: unknown): maybeSet is Set<unknown>;
+
+    /**
+     * Creates a new Set containing `values`.
+     */
+    function of<T>(...values: Array<T>): Set<T>;
+
+    /**
+     * `Set.fromKeys()` creates a new immutable Set containing the keys from
+     * this Collection or JavaScript Object.
+     */
+    function fromKeys<T>(iter: Collection.Keyed<T, unknown>): Set<T>;
+    function fromKeys<T>(iter: Collection<T, unknown>): Set<T>;
+    function fromKeys(obj: { [key: string]: unknown }): Set<string>;
+
+    /**
+     * `Set.intersect()` creates a new immutable Set that is the intersection of
+     * a collection of other sets.
+     *
+     * ```js
+     * const { Set } = require('immutable')
+     * const intersected = Set.intersect([
+     *   Set([ 'a', 'b', 'c' ])
+     *   Set([ 'c', 'a', 't' ])
+     * ])
+     * // Set [ "a", "c" ]
+     * ```
+     */
+    function intersect<T>(sets: Iterable<Iterable<T>>): Set<T>;
+
+    /**
+     * `Set.union()` creates a new immutable Set that is the union of a
+     * collection of other sets.
+     *
+     * ```js
+     * const { Set } = require('immutable')
+     * const unioned = Set.union([
+     *   Set([ 'a', 'b', 'c' ])
+     *   Set([ 'c', 'a', 't' ])
+     * ])
+     * // Set [ "a", "b", "c", "t" ]
+     * ```
+     */
+    function union<T>(sets: Iterable<Iterable<T>>): Set<T>;
+  }
+
+  /**
+   * Create a new immutable Set containing the values of the provided
+   * collection-like.
+   *
+   * Note: `Set` is a factory function and not a class, and does not use the
+   * `new` keyword during construction.
+   */
+  function Set<T>(collection?: Iterable<T> | ArrayLike<T>): Set<T>;
+
+  interface Set<T> extends Collection.Set<T> {
+    /**
+     * The number of items in this Set.
+     */
+    readonly size: number;
+
+    // Persistent changes
+
+    /**
+     * Returns a new Set which also includes this value.
+     *
+     * Note: `add` can be used in `withMutations`.
+     */
+    add(value: T): this;
+
+    /**
+     * Returns a new Set which excludes this value.
+     *
+     * Note: `delete` can be used in `withMutations`.
+     *
+     * Note: `delete` **cannot** be safely used in IE8, use `remove` if
+     * supporting old browsers.
+     *
+     * @alias remove
+     */
+    delete(value: T): this;
+    remove(value: T): this;
+
+    /**
+     * Returns a new Set containing no values.
+     *
+     * Note: `clear` can be used in `withMutations`.
+     */
+    clear(): this;
+
+    /**
+     * Returns a Set including any value from `collections` that does not already
+     * exist in this Set.
+     *
+     * Note: `union` can be used in `withMutations`.
+     * @alias merge
+     * @alias concat
+     */
+    union<C>(...collections: Array<Iterable<C>>): Set<T | C>;
+    merge<C>(...collections: Array<Iterable<C>>): Set<T | C>;
+    concat<C>(...collections: Array<Iterable<C>>): Set<T | C>;
+
+    /**
+     * Returns a Set which has removed any values not also contained
+     * within `collections`.
+     *
+     * Note: `intersect` can be used in `withMutations`.
+     */
+    intersect(...collections: Array<Iterable<T>>): this;
+
+    /**
+     * Returns a Set excluding any values contained within `collections`.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { OrderedSet } = require('immutable')
+     * OrderedSet([ 1, 2, 3 ]).subtract([1, 3])
+     * // OrderedSet [2]
+     * ```
+     *
+     * Note: `subtract` can be used in `withMutations`.
+     */
+    subtract(...collections: Array<Iterable<T>>): this;
+
+    // Transient changes
+
+    /**
+     * Note: Not all methods can be used on a mutable collection or within
+     * `withMutations`! Check the documentation for each method to see if it
+     * mentions being safe to use in `withMutations`.
+     *
+     * @see `Map#withMutations`
+     */
+    withMutations(mutator: (mutable: this) => unknown): this;
+
+    /**
+     * Note: Not all methods can be used on a mutable collection or within
+     * `withMutations`! Check the documentation for each method to see if it
+     * mentions being safe to use in `withMutations`.
+     *
+     * @see `Map#asMutable`
+     */
+    asMutable(): this;
+
+    /**
+     * @see `Map#wasAltered`
+     */
+    wasAltered(): boolean;
+
+    /**
+     * @see `Map#asImmutable`
+     */
+    asImmutable(): this;
+
+    // Sequence algorithms
+
+    /**
+     * Returns a new Set with values passed through a
+     * `mapper` function.
+     *
+     *     Set([1,2]).map(x => 10 * x)
+     *     // Set [10,20]
+     */
+    map<M>(
+      mapper: (value: T, key: T, iter: this) => M,
+      context?: unknown
+    ): Set<M>;
+
+    /**
+     * Flat-maps the Set, returning a new Set.
+     *
+     * Similar to `set.map(...).flatten(true)`.
+     */
+    flatMap<M>(
+      mapper: (value: T, key: T, iter: this) => Iterable<M>,
+      context?: unknown
+    ): Set<M>;
+
+    /**
+     * Returns a new Set with only the values for which the `predicate`
+     * function returns true.
+     *
+     * Note: `filter()` always returns a new instance, even if it results in
+     * not filtering out any values.
+     */
+    filter<F extends T>(
+      predicate: (value: T, key: T, iter: this) => value is F,
+      context?: unknown
+    ): Set<F>;
+    filter(
+      predicate: (value: T, key: T, iter: this) => unknown,
+      context?: unknown
+    ): this;
+
+    /**
+     * Returns a new Set with the values for which the `predicate` function
+     * returns false and another for which is returns true.
+     */
+    partition<F extends T, C>(
+      predicate: (this: C, value: T, key: T, iter: this) => value is F,
+      context?: C
+    ): [Set<T>, Set<F>];
+    partition<C>(
+      predicate: (this: C, value: T, key: T, iter: this) => unknown,
+      context?: C
+    ): [this, this];
+
+    /**
+     * Returns an OrderedSet of the same type which includes the same entries,
+     * stably sorted by using a `comparator`.
+     *
+     * If a `comparator` is not provided, a default comparator uses `<` and `>`.
+     *
+     * `comparator(valueA, valueB)`:
+     *
+     *   * Returns `0` if the elements should not be swapped.
+     *   * Returns `-1` (or any negative number) if `valueA` comes before `valueB`
+     *   * Returns `1` (or any positive number) if `valueA` comes after `valueB`
+     *   * Alternatively, can return a value of the `PairSorting` enum type
+     *   * Is pure, i.e. it must always return the same value for the same pair
+     *     of values.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Set } = require('immutable')
+     * Set(['b', 'a', 'c']).sort((a, b) => {
+     *   if (a < b) { return -1; }
+     *   if (a > b) { return 1; }
+     *   if (a === b) { return 0; }
+     * });
+     * // OrderedSet { "a":, "b", "c" }
+     * ```
+     *
+     * Note: `sort()` Always returns a new instance, even if the original was
+     * already sorted.
+     *
+     * Note: This is always an eager operation.
+     */
+    sort(comparator?: Comparator<T>): this & OrderedSet<T>;
+
+    /**
+     * Like `sort`, but also accepts a `comparatorValueMapper` which allows for
+     * sorting by more sophisticated means:
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Set } = require('immutable')
+     * const beattles = Set([
+     *   { name: "Lennon" },
+     *   { name: "McCartney" },
+     *   { name: "Harrison" },
+     *   { name: "Starr" },
+     * ]);
+     * beattles.sortBy(member => member.name);
+     * ```
+     *
+     * Note: `sortBy()` Always returns a new instance, even if the original was
+     * already sorted.
+     *
+     * Note: This is always an eager operation.
+     */
+    sortBy<C>(
+      comparatorValueMapper: (value: T, key: T, iter: this) => C,
+      comparator?: (valueA: C, valueB: C) => number
+    ): this & OrderedSet<T>;
+  }
+
+  /**
+   * A type of Set that has the additional guarantee that the iteration order of
+   * values will be the order in which they were `add`ed.
+   *
+   * The iteration behavior of OrderedSet is the same as native ES6 Set.
+   *
+   * Note that `OrderedSet` are more expensive than non-ordered `Set` and may
+   * consume more memory. `OrderedSet#add` is amortized O(log32 N), but not
+   * stable.
+   */
+  namespace OrderedSet {
+    /**
+     * True if the provided value is an OrderedSet.
+     */
+    function isOrderedSet(
+      maybeOrderedSet: unknown
+    ): maybeOrderedSet is OrderedSet<unknown>;
+
+    /**
+     * Creates a new OrderedSet containing `values`.
+     */
+    function of<T>(...values: Array<T>): OrderedSet<T>;
+
+    /**
+     * `OrderedSet.fromKeys()` creates a new immutable OrderedSet containing
+     * the keys from this Collection or JavaScript Object.
+     */
+    function fromKeys<T>(iter: Collection.Keyed<T, unknown>): OrderedSet<T>;
+    function fromKeys<T>(iter: Collection<T, unknown>): OrderedSet<T>;
+    function fromKeys(obj: { [key: string]: unknown }): OrderedSet<string>;
+  }
+
+  /**
+   * Create a new immutable OrderedSet containing the values of the provided
+   * collection-like.
+   *
+   * Note: `OrderedSet` is a factory function and not a class, and does not use
+   * the `new` keyword during construction.
+   */
+  function OrderedSet<T>(
+    collection?: Iterable<T> | ArrayLike<T>
+  ): OrderedSet<T>;
+
+  interface OrderedSet<T> extends Set<T> {
+    /**
+     * The number of items in this OrderedSet.
+     */
+    readonly size: number;
+
+    /**
+     * Returns an OrderedSet including any value from `collections` that does
+     * not already exist in this OrderedSet.
+     *
+     * Note: `union` can be used in `withMutations`.
+     * @alias merge
+     * @alias concat
+     */
+    union<C>(...collections: Array<Iterable<C>>): OrderedSet<T | C>;
+    merge<C>(...collections: Array<Iterable<C>>): OrderedSet<T | C>;
+    concat<C>(...collections: Array<Iterable<C>>): OrderedSet<T | C>;
+
+    // Sequence algorithms
+
+    /**
+     * Returns a new Set with values passed through a
+     * `mapper` function.
+     *
+     *     OrderedSet([ 1, 2 ]).map(x => 10 * x)
+     *     // OrderedSet [10, 20]
+     */
+    map<M>(
+      mapper: (value: T, key: T, iter: this) => M,
+      context?: unknown
+    ): OrderedSet<M>;
+
+    /**
+     * Flat-maps the OrderedSet, returning a new OrderedSet.
+     *
+     * Similar to `set.map(...).flatten(true)`.
+     */
+    flatMap<M>(
+      mapper: (value: T, key: T, iter: this) => Iterable<M>,
+      context?: unknown
+    ): OrderedSet<M>;
+
+    /**
+     * Returns a new OrderedSet with only the values for which the `predicate`
+     * function returns true.
+     *
+     * Note: `filter()` always returns a new instance, even if it results in
+     * not filtering out any values.
+     */
+    filter<F extends T>(
+      predicate: (value: T, key: T, iter: this) => value is F,
+      context?: unknown
+    ): OrderedSet<F>;
+    filter(
+      predicate: (value: T, key: T, iter: this) => unknown,
+      context?: unknown
+    ): this;
+
+    /**
+     * Returns a new OrderedSet with the values for which the `predicate`
+     * function returns false and another for which is returns true.
+     */
+    partition<F extends T, C>(
+      predicate: (this: C, value: T, key: T, iter: this) => value is F,
+      context?: C
+    ): [OrderedSet<T>, OrderedSet<F>];
+    partition<C>(
+      predicate: (this: C, value: T, key: T, iter: this) => unknown,
+      context?: C
+    ): [this, this];
+
+    /**
+     * Returns an OrderedSet of the same type "zipped" with the provided
+     * collections.
+     *
+     * Like `zipWith`, but using the default `zipper`: creating an `Array`.
+     *
+     * ```js
+     * const a = OrderedSet([ 1, 2, 3 ])
+     * const b = OrderedSet([ 4, 5, 6 ])
+     * const c = a.zip(b)
+     * // OrderedSet [ [ 1, 4 ], [ 2, 5 ], [ 3, 6 ] ]
+     * ```
+     */
+    zip<U>(other: Collection<unknown, U>): OrderedSet<[T, U]>;
+    zip<U, V>(
+      other1: Collection<unknown, U>,
+      other2: Collection<unknown, V>
+    ): OrderedSet<[T, U, V]>;
+    zip(
+      ...collections: Array<Collection<unknown, unknown>>
+    ): OrderedSet<unknown>;
+
+    /**
+     * Returns a OrderedSet of the same type "zipped" with the provided
+     * collections.
+     *
+     * Unlike `zip`, `zipAll` continues zipping until the longest collection is
+     * exhausted. Missing values from shorter collections are filled with `undefined`.
+     *
+     * ```js
+     * const a = OrderedSet([ 1, 2 ]);
+     * const b = OrderedSet([ 3, 4, 5 ]);
+     * const c = a.zipAll(b); // OrderedSet [ [ 1, 3 ], [ 2, 4 ], [ undefined, 5 ] ]
+     * ```
+     *
+     * Note: Since zipAll will return a collection as large as the largest
+     * input, some results may contain undefined values. TypeScript cannot
+     * account for these without cases (as of v2.5).
+     */
+    zipAll<U>(other: Collection<unknown, U>): OrderedSet<[T, U]>;
+    zipAll<U, V>(
+      other1: Collection<unknown, U>,
+      other2: Collection<unknown, V>
+    ): OrderedSet<[T, U, V]>;
+    zipAll(
+      ...collections: Array<Collection<unknown, unknown>>
+    ): OrderedSet<unknown>;
+
+    /**
+     * Returns an OrderedSet of the same type "zipped" with the provided
+     * collections by using a custom `zipper` function.
+     *
+     * @see Seq.Indexed.zipWith
+     */
+    zipWith<U, Z>(
+      zipper: (value: T, otherValue: U) => Z,
+      otherCollection: Collection<unknown, U>
+    ): OrderedSet<Z>;
+    zipWith<U, V, Z>(
+      zipper: (value: T, otherValue: U, thirdValue: V) => Z,
+      otherCollection: Collection<unknown, U>,
+      thirdCollection: Collection<unknown, V>
+    ): OrderedSet<Z>;
+    zipWith<Z>(
+      zipper: (...values: Array<unknown>) => Z,
+      ...collections: Array<Collection<unknown, unknown>>
+    ): OrderedSet<Z>;
+  }
+
+  /**
+   * Stacks are indexed collections which support very efficient O(1) addition
+   * and removal from the front using `unshift(v)` and `shift()`.
+   *
+   * For familiarity, Stack also provides `push(v)`, `pop()`, and `peek()`, but
+   * be aware that they also operate on the front of the list, unlike List or
+   * a JavaScript Array.
+   *
+   * Note: `reverse()` or any inherent reverse traversal (`reduceRight`,
+   * `lastIndexOf`, etc.) is not efficient with a Stack.
+   *
+   * Stack is implemented with a Single-Linked List.
+   */
+  namespace Stack {
+    /**
+     * True if the provided value is a Stack
+     */
+    function isStack(maybeStack: unknown): maybeStack is Stack<unknown>;
+
+    /**
+     * Creates a new Stack containing `values`.
+     */
+    function of<T>(...values: Array<T>): Stack<T>;
+  }
+
+  /**
+   * Create a new immutable Stack containing the values of the provided
+   * collection-like.
+   *
+   * The iteration order of the provided collection is preserved in the
+   * resulting `Stack`.
+   *
+   * Note: `Stack` is a factory function and not a class, and does not use the
+   * `new` keyword during construction.
+   */
+  function Stack<T>(collection?: Iterable<T> | ArrayLike<T>): Stack<T>;
+
+  interface Stack<T> extends Collection.Indexed<T> {
+    /**
+     * The number of items in this Stack.
+     */
+    readonly size: number;
+
+    // Reading values
+
+    /**
+     * Alias for `Stack.first()`.
+     */
+    peek(): T | undefined;
+
+    // Persistent changes
+
+    /**
+     * Returns a new Stack with 0 size and no values.
+     *
+     * Note: `clear` can be used in `withMutations`.
+     */
+    clear(): Stack<T>;
+
+    /**
+     * Returns a new Stack with the provided `values` prepended, shifting other
+     * values ahead to higher indices.
+     *
+     * This is very efficient for Stack.
+     *
+     * Note: `unshift` can be used in `withMutations`.
+     */
+    unshift(...values: Array<T>): Stack<T>;
+
+    /**
+     * Like `Stack#unshift`, but accepts a collection rather than varargs.
+     *
+     * Note: `unshiftAll` can be used in `withMutations`.
+     */
+    unshiftAll(iter: Iterable<T>): Stack<T>;
+
+    /**
+     * Returns a new Stack with a size ones less than this Stack, excluding
+     * the first item in this Stack, shifting all other values to a lower index.
+     *
+     * Note: this differs from `Array#shift` because it returns a new
+     * Stack rather than the removed value. Use `first()` or `peek()` to get the
+     * first value in this Stack.
+     *
+     * Note: `shift` can be used in `withMutations`.
+     */
+    shift(): Stack<T>;
+
+    /**
+     * Alias for `Stack#unshift` and is not equivalent to `List#push`.
+     */
+    push(...values: Array<T>): Stack<T>;
+
+    /**
+     * Alias for `Stack#unshiftAll`.
+     */
+    pushAll(iter: Iterable<T>): Stack<T>;
+
+    /**
+     * Alias for `Stack#shift` and is not equivalent to `List#pop`.
+     */
+    pop(): Stack<T>;
+
+    // Transient changes
+
+    /**
+     * Note: Not all methods can be used on a mutable collection or within
+     * `withMutations`! Check the documentation for each method to see if it
+     * mentions being safe to use in `withMutations`.
+     *
+     * @see `Map#withMutations`
+     */
+    withMutations(mutator: (mutable: this) => unknown): this;
+
+    /**
+     * Note: Not all methods can be used on a mutable collection or within
+     * `withMutations`! Check the documentation for each method to see if it
+     * mentions being safe to use in `withMutations`.
+     *
+     * @see `Map#asMutable`
+     */
+    asMutable(): this;
+
+    /**
+     * @see `Map#wasAltered`
+     */
+    wasAltered(): boolean;
+
+    /**
+     * @see `Map#asImmutable`
+     */
+    asImmutable(): this;
+
+    // Sequence algorithms
+
+    /**
+     * Returns a new Stack with other collections concatenated to this one.
+     */
+    concat<C>(...valuesOrCollections: Array<Iterable<C> | C>): Stack<T | C>;
+
+    /**
+     * Returns a new Stack with values passed through a
+     * `mapper` function.
+     *
+     *     Stack([ 1, 2 ]).map(x => 10 * x)
+     *     // Stack [ 10, 20 ]
+     *
+     * Note: `map()` always returns a new instance, even if it produced the same
+     * value at every step.
+     */
+    map<M>(
+      mapper: (value: T, key: number, iter: this) => M,
+      context?: unknown
+    ): Stack<M>;
+
+    /**
+     * Flat-maps the Stack, returning a new Stack.
+     *
+     * Similar to `stack.map(...).flatten(true)`.
+     */
+    flatMap<M>(
+      mapper: (value: T, key: number, iter: this) => Iterable<M>,
+      context?: unknown
+    ): Stack<M>;
+
+    /**
+     * Returns a new Set with only the values for which the `predicate`
+     * function returns true.
+     *
+     * Note: `filter()` always returns a new instance, even if it results in
+     * not filtering out any values.
+     */
+    filter<F extends T>(
+      predicate: (value: T, index: number, iter: this) => value is F,
+      context?: unknown
+    ): Set<F>;
+    filter(
+      predicate: (value: T, index: number, iter: this) => unknown,
+      context?: unknown
+    ): this;
+
+    /**
+     * Returns a Stack "zipped" with the provided collections.
+     *
+     * Like `zipWith`, but using the default `zipper`: creating an `Array`.
+     *
+     * ```js
+     * const a = Stack([ 1, 2, 3 ]);
+     * const b = Stack([ 4, 5, 6 ]);
+     * const c = a.zip(b); // Stack [ [ 1, 4 ], [ 2, 5 ], [ 3, 6 ] ]
+     * ```
+     */
+    zip<U>(other: Collection<unknown, U>): Stack<[T, U]>;
+    zip<U, V>(
+      other: Collection<unknown, U>,
+      other2: Collection<unknown, V>
+    ): Stack<[T, U, V]>;
+    zip(...collections: Array<Collection<unknown, unknown>>): Stack<unknown>;
+
+    /**
+     * Returns a Stack "zipped" with the provided collections.
+     *
+     * Unlike `zip`, `zipAll` continues zipping until the longest collection is
+     * exhausted. Missing values from shorter collections are filled with `undefined`.
+     *
+     * ```js
+     * const a = Stack([ 1, 2 ]);
+     * const b = Stack([ 3, 4, 5 ]);
+     * const c = a.zipAll(b); // Stack [ [ 1, 3 ], [ 2, 4 ], [ undefined, 5 ] ]
+     * ```
+     *
+     * Note: Since zipAll will return a collection as large as the largest
+     * input, some results may contain undefined values. TypeScript cannot
+     * account for these without cases (as of v2.5).
+     */
+    zipAll<U>(other: Collection<unknown, U>): Stack<[T, U]>;
+    zipAll<U, V>(
+      other: Collection<unknown, U>,
+      other2: Collection<unknown, V>
+    ): Stack<[T, U, V]>;
+    zipAll(...collections: Array<Collection<unknown, unknown>>): Stack<unknown>;
+
+    /**
+     * Returns a Stack "zipped" with the provided collections by using a
+     * custom `zipper` function.
+     *
+     * ```js
+     * const a = Stack([ 1, 2, 3 ]);
+     * const b = Stack([ 4, 5, 6 ]);
+     * const c = a.zipWith((a, b) => a + b, b);
+     * // Stack [ 5, 7, 9 ]
+     * ```
+     */
+    zipWith<U, Z>(
+      zipper: (value: T, otherValue: U) => Z,
+      otherCollection: Collection<unknown, U>
+    ): Stack<Z>;
+    zipWith<U, V, Z>(
+      zipper: (value: T, otherValue: U, thirdValue: V) => Z,
+      otherCollection: Collection<unknown, U>,
+      thirdCollection: Collection<unknown, V>
+    ): Stack<Z>;
+    zipWith<Z>(
+      zipper: (...values: Array<unknown>) => Z,
+      ...collections: Array<Collection<unknown, unknown>>
+    ): Stack<Z>;
+  }
+
+  /**
+   * Returns a Seq.Indexed of numbers from `start` (inclusive) to `end`
+   * (exclusive), by `step`, where `start` defaults to 0, `step` to 1, and `end` to
+   * infinity. When `start` is equal to `end`, returns empty range.
+   *
+   * Note: `Range` is a factory function and not a class, and does not use the
+   * `new` keyword during construction.
+   *
+   * ```js
+   * const { Range } = require('immutable')
+   * Range() // [ 0, 1, 2, 3, ... ]
+   * Range(10) // [ 10, 11, 12, 13, ... ]
+   * Range(10, 15) // [ 10, 11, 12, 13, 14 ]
+   * Range(10, 30, 5) // [ 10, 15, 20, 25 ]
+   * Range(30, 10, 5) // [ 30, 25, 20, 15 ]
+   * Range(30, 30, 5) // []
+   * ```
+   */
+  function Range(
+    start: number,
+    end: number,
+    step?: number
+  ): Seq.Indexed<number>;
+
+  /**
+   * Returns a Seq.Indexed of `value` repeated `times` times. When `times` is
+   * not defined, returns an infinite `Seq` of `value`.
+   *
+   * Note: `Repeat` is a factory function and not a class, and does not use the
+   * `new` keyword during construction.
+   *
+   * ```js
+   * const { Repeat } = require('immutable')
+   * Repeat('foo') // [ 'foo', 'foo', 'foo', ... ]
+   * Repeat('bar', 4) // [ 'bar', 'bar', 'bar', 'bar' ]
+   * ```
+   */
+  function Repeat<T>(value: T, times?: number): Seq.Indexed<T>;
+
+  /**
+   * A record is similar to a JS object, but enforces a specific set of allowed
+   * string keys, and has default values.
+   *
+   * The `Record()` function produces new Record Factories, which when called
+   * create Record instances.
+   *
+   * ```js
+   * const { Record } = require('immutable')
+   * const ABRecord = Record({ a: 1, b: 2 })
+   * const myRecord = ABRecord({ b: 3 })
+   * ```
+   *
+   * Records always have a value for the keys they define. `remove`ing a key
+   * from a record simply resets it to the default value for that key.
+   *
+   * ```js
+   * myRecord.get('a') // 1
+   * myRecord.get('b') // 3
+   * const myRecordWithoutB = myRecord.remove('b')
+   * myRecordWithoutB.get('b') // 2
+   * ```
+   *
+   * Values provided to the constructor not found in the Record type will
+   * be ignored. For example, in this case, ABRecord is provided a key "x" even
+   * though only "a" and "b" have been defined. The value for "x" will be
+   * ignored for this record.
+   *
+   * ```js
+   * const myRecord = ABRecord({ b: 3, x: 10 })
+   * myRecord.get('x') // undefined
+   * ```
+   *
+   * Because Records have a known set of string keys, property get access works
+   * as expected, however property sets will throw an Error.
+   *
+   * Note: IE8 does not support property access. Only use `get()` when
+   * supporting IE8.
+   *
+   * ```js
+   * myRecord.b // 3
+   * myRecord.b = 5 // throws Error
+   * ```
+   *
+   * Record Types can be extended as well, allowing for custom methods on your
+   * Record. This is not a common pattern in functional environments, but is in
+   * many JS programs.
+   *
+   * However Record Types are more restricted than typical JavaScript classes.
+   * They do not use a class constructor, which also means they cannot use
+   * class properties (since those are technically part of a constructor).
+   *
+   * While Record Types can be syntactically created with the JavaScript `class`
+   * form, the resulting Record function is actually a factory function, not a
+   * class constructor. Even though Record Types are not classes, JavaScript
+   * currently requires the use of `new` when creating new Record instances if
+   * they are defined as a `class`.
+   *
+   * ```
+   * class ABRecord extends Record({ a: 1, b: 2 }) {
+   *   getAB() {
+   *     return this.a + this.b;
+   *   }
+   * }
+   *
+   * var myRecord = new ABRecord({b: 3})
+   * myRecord.getAB() // 4
+   * ```
+   *
+   *
+   * **Flow Typing Records:**
+   *
+   * Immutable.js exports two Flow types designed to make it easier to use
+   * Records with flow typed code, `RecordOf<TProps>` and `RecordFactory<TProps>`.
+   *
+   * When defining a new kind of Record factory function, use a flow type that
+   * describes the values the record contains along with `RecordFactory<TProps>`.
+   * To type instances of the Record (which the factory function returns),
+   * use `RecordOf<TProps>`.
+   *
+   * Typically, new Record definitions will export both the Record factory
+   * function as well as the Record instance type for use in other code.
+   *
+   * ```js
+   * import type { RecordFactory, RecordOf } from 'immutable';
+   *
+   * // Use RecordFactory<TProps> for defining new Record factory functions.
+   * type Point3DProps = { x: number, y: number, z: number };
+   * const defaultValues: Point3DProps = { x: 0, y: 0, z: 0 };
+   * const makePoint3D: RecordFactory<Point3DProps> = Record(defaultValues);
+   * export makePoint3D;
+   *
+   * // Use RecordOf<T> for defining new instances of that Record.
+   * export type Point3D = RecordOf<Point3DProps>;
+   * const some3DPoint: Point3D = makePoint3D({ x: 10, y: 20, z: 30 });
+   * ```
+   *
+   * **Flow Typing Record Subclasses:**
+   *
+   * Records can be subclassed as a means to add additional methods to Record
+   * instances. This is generally discouraged in favor of a more functional API,
+   * since Subclasses have some minor overhead. However the ability to create
+   * a rich API on Record types can be quite valuable.
+   *
+   * When using Flow to type Subclasses, do not use `RecordFactory<TProps>`,
+   * instead apply the props type when subclassing:
+   *
+   * ```js
+   * type PersonProps = {name: string, age: number};
+   * const defaultValues: PersonProps = {name: 'Aristotle', age: 2400};
+   * const PersonRecord = Record(defaultValues);
+   * class Person extends PersonRecord<PersonProps> {
+   *   getName(): string {
+   *     return this.get('name')
+   *   }
+   *
+   *   setName(name: string): this {
+   *     return this.set('name', name);
+   *   }
+   * }
+   * ```
+   *
+   * **Choosing Records vs plain JavaScript objects**
+   *
+   * Records offer a persistently immutable alternative to plain JavaScript
+   * objects, however they're not required to be used within Immutable.js
+   * collections. In fact, the deep-access and deep-updating functions
+   * like `getIn()` and `setIn()` work with plain JavaScript Objects as well.
+   *
+   * Deciding to use Records or Objects in your application should be informed
+   * by the tradeoffs and relative benefits of each:
+   *
+   * - *Runtime immutability*: plain JS objects may be carefully treated as
+   *   immutable, however Record instances will *throw* if attempted to be
+   *   mutated directly. Records provide this additional guarantee, however at
+   *   some marginal runtime cost. While JS objects are mutable by nature, the
+   *   use of type-checking tools like [Flow](https://medium.com/@gcanti/immutability-with-flow-faa050a1aef4)
+   *   can help gain confidence in code written to favor immutability.
+   *
+   * - *Value equality*: Records use value equality when compared with `is()`
+   *   or `record.equals()`. That is, two Records with the same keys and values
+   *   are equal. Plain objects use *reference equality*. Two objects with the
+   *   same keys and values are not equal since they are different objects.
+   *   This is important to consider when using objects as keys in a `Map` or
+   *   values in a `Set`, which use equality when retrieving values.
+   *
+   * - *API methods*: Records have a full featured API, with methods like
+   *   `.getIn()`, and `.equals()`. These can make working with these values
+   *   easier, but comes at the cost of not allowing keys with those names.
+   *
+   * - *Default values*: Records provide default values for every key, which
+   *   can be useful when constructing Records with often unchanging values.
+   *   However default values can make using Flow and TypeScript more laborious.
+   *
+   * - *Serialization*: Records use a custom internal representation to
+   *   efficiently store and update their values. Converting to and from this
+   *   form isn't free. If converting Records to plain objects is common,
+   *   consider sticking with plain objects to begin with.
+   */
+  namespace Record {
+    /**
+     * True if `maybeRecord` is an instance of a Record.
+     */
+    function isRecord(maybeRecord: unknown): maybeRecord is Record<{}>;
+
+    /**
+     * Records allow passing a second parameter to supply a descriptive name
+     * that appears when converting a Record to a string or in any error
+     * messages. A descriptive name for any record can be accessed by using this
+     * method. If one was not provided, the string "Record" is returned.
+     *
+     * ```js
+     * const { Record } = require('immutable')
+     * const Person = Record({
+     *   name: null
+     * }, 'Person')
+     *
+     * var me = Person({ name: 'My Name' })
+     * me.toString() // "Person { "name": "My Name" }"
+     * Record.getDescriptiveName(me) // "Person"
+     * ```
+     */
+    function getDescriptiveName(record: Record<any>): string;
+
+    /**
+     * A Record.Factory is created by the `Record()` function. Record instances
+     * are created by passing it some of the accepted values for that Record
+     * type:
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { Record } = require('immutable')" }
+     * -->
+     * ```js
+     * // makePerson is a Record Factory function
+     * const makePerson = Record({ name: null, favoriteColor: 'unknown' });
+     *
+     * // alan is a Record instance
+     * const alan = makePerson({ name: 'Alan' });
+     * ```
+     *
+     * Note that Record Factories return `Record<TProps> & Readonly<TProps>`,
+     * this allows use of both the Record instance API, and direct property
+     * access on the resulting instances:
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { Record } = require('immutable');const makePerson = Record({ name: null, favoriteColor: 'unknown' });const alan = makePerson({ name: 'Alan' });" }
+     * -->
+     * ```js
+     * // Use the Record API
+     * console.log('Record API: ' + alan.get('name'))
+     *
+     * // Or direct property access (Readonly)
+     * console.log('property access: ' + alan.name)
+     * ```
+     *
+     * **Flow Typing Records:**
+     *
+     * Use the `RecordFactory<TProps>` Flow type to get high quality type checking of
+     * Records:
+     *
+     * ```js
+     * import type { RecordFactory, RecordOf } from 'immutable';
+     *
+     * // Use RecordFactory<TProps> for defining new Record factory functions.
+     * type PersonProps = { name: ?string, favoriteColor: string };
+     * const makePerson: RecordFactory<PersonProps> = Record({ name: null, favoriteColor: 'unknown' });
+     *
+     * // Use RecordOf<T> for defining new instances of that Record.
+     * type Person = RecordOf<PersonProps>;
+     * const alan: Person = makePerson({ name: 'Alan' });
+     * ```
+     */
+    namespace Factory {}
+
+    interface Factory<TProps extends object> {
+      (values?: Partial<TProps> | Iterable<[string, unknown]>): Record<TProps> &
+        Readonly<TProps>;
+      new (
+        values?: Partial<TProps> | Iterable<[string, unknown]>
+      ): Record<TProps> & Readonly<TProps>;
+
+      /**
+       * The name provided to `Record(values, name)` can be accessed with
+       * `displayName`.
+       */
+      displayName: string;
+    }
+
+    function Factory<TProps extends object>(
+      values?: Partial<TProps> | Iterable<[string, unknown]>
+    ): Record<TProps> & Readonly<TProps>;
+  }
+
+  /**
+   * Unlike other types in Immutable.js, the `Record()` function creates a new
+   * Record Factory, which is a function that creates Record instances.
+   *
+   * See above for examples of using `Record()`.
+   *
+   * Note: `Record` is a factory function and not a class, and does not use the
+   * `new` keyword during construction.
+   */
+  function Record<TProps extends object>(
+    defaultValues: TProps,
+    name?: string
+  ): Record.Factory<TProps>;
+
+  interface Record<TProps extends object> {
+    // Reading values
+
+    has(key: string): key is keyof TProps & string;
+
+    /**
+     * Returns the value associated with the provided key, which may be the
+     * default value defined when creating the Record factory function.
+     *
+     * If the requested key is not defined by this Record type, then
+     * notSetValue will be returned if provided. Note that this scenario would
+     * produce an error when using Flow or TypeScript.
+     */
+    get<K extends keyof TProps>(key: K, notSetValue?: unknown): TProps[K];
+    get<T>(key: string, notSetValue: T): T;
+
+    // Reading deep values
+
+    hasIn(keyPath: Iterable<unknown>): boolean;
+    getIn(keyPath: Iterable<unknown>): unknown;
+
+    // Value equality
+
+    equals(other: unknown): boolean;
+    hashCode(): number;
+
+    // Persistent changes
+
+    set<K extends keyof TProps>(key: K, value: TProps[K]): this;
+    update<K extends keyof TProps>(
+      key: K,
+      updater: (value: TProps[K]) => TProps[K]
+    ): this;
+    merge(
+      ...collections: Array<Partial<TProps> | Iterable<[string, unknown]>>
+    ): this;
+    mergeDeep(
+      ...collections: Array<Partial<TProps> | Iterable<[string, unknown]>>
+    ): this;
+
+    mergeWith(
+      merger: (oldVal: unknown, newVal: unknown, key: keyof TProps) => unknown,
+      ...collections: Array<Partial<TProps> | Iterable<[string, unknown]>>
+    ): this;
+    mergeDeepWith(
+      merger: (oldVal: unknown, newVal: unknown, key: unknown) => unknown,
+      ...collections: Array<Partial<TProps> | Iterable<[string, unknown]>>
+    ): this;
+
+    /**
+     * Returns a new instance of this Record type with the value for the
+     * specific key set to its default value.
+     *
+     * @alias remove
+     */
+    delete<K extends keyof TProps>(key: K): this;
+    remove<K extends keyof TProps>(key: K): this;
+
+    /**
+     * Returns a new instance of this Record type with all values set
+     * to their default values.
+     */
+    clear(): this;
+
+    // Deep persistent changes
+
+    setIn(keyPath: Iterable<unknown>, value: unknown): this;
+    updateIn(
+      keyPath: Iterable<unknown>,
+      updater: (value: unknown) => unknown
+    ): this;
+    mergeIn(keyPath: Iterable<unknown>, ...collections: Array<unknown>): this;
+    mergeDeepIn(
+      keyPath: Iterable<unknown>,
+      ...collections: Array<unknown>
+    ): this;
+
+    /**
+     * @alias removeIn
+     */
+    deleteIn(keyPath: Iterable<unknown>): this;
+    removeIn(keyPath: Iterable<unknown>): this;
+
+    // Conversion to JavaScript types
+
+    /**
+     * Deeply converts this Record to equivalent native JavaScript Object.
+     *
+     * Note: This method may not be overridden. Objects with custom
+     * serialization to plain JS may override toJSON() instead.
+     */
+    toJS(): DeepCopy<TProps>;
+
+    /**
+     * Shallowly converts this Record to equivalent native JavaScript Object.
+     */
+    toJSON(): TProps;
+
+    /**
+     * Shallowly converts this Record to equivalent JavaScript Object.
+     */
+    toObject(): TProps;
+
+    // Transient changes
+
+    /**
+     * Note: Not all methods can be used on a mutable collection or within
+     * `withMutations`! Only `set` may be used mutatively.
+     *
+     * @see `Map#withMutations`
+     */
+    withMutations(mutator: (mutable: this) => unknown): this;
+
+    /**
+     * @see `Map#asMutable`
+     */
+    asMutable(): this;
+
+    /**
+     * @see `Map#wasAltered`
+     */
+    wasAltered(): boolean;
+
+    /**
+     * @see `Map#asImmutable`
+     */
+    asImmutable(): this;
+
+    // Sequence algorithms
+
+    toSeq(): Seq.Keyed<keyof TProps, TProps[keyof TProps]>;
+
+    [Symbol.iterator](): IterableIterator<[keyof TProps, TProps[keyof TProps]]>;
+  }
+
+  /**
+   * RecordOf<T> is used in TypeScript to define interfaces expecting an
+   * instance of record with type T.
+   *
+   * This is equivalent to an instance of a record created by a Record Factory.
+   */
+  type RecordOf<TProps extends object> = Record<TProps> & Readonly<TProps>;
+
+  /**
+   * `Seq` describes a lazy operation, allowing them to efficiently chain
+   * use of all the higher-order collection methods (such as `map` and `filter`)
+   * by not creating intermediate collections.
+   *
+   * **Seq is immutable** — Once a Seq is created, it cannot be
+   * changed, appended to, rearranged or otherwise modified. Instead, any
+   * mutative method called on a `Seq` will return a new `Seq`.
+   *
+   * **Seq is lazy** — `Seq` does as little work as necessary to respond to any
+   * method call. Values are often created during iteration, including implicit
+   * iteration when reducing or converting to a concrete data structure such as
+   * a `List` or JavaScript `Array`.
+   *
+   * For example, the following performs no work, because the resulting
+   * `Seq`'s values are never iterated:
+   *
+   * ```js
+   * const { Seq } = require('immutable')
+   * const oddSquares = Seq([ 1, 2, 3, 4, 5, 6, 7, 8 ])
+   *   .filter(x => x % 2 !== 0)
+   *   .map(x => x * x)
+   * ```
+   *
+   * Once the `Seq` is used, it performs only the work necessary. In this
+   * example, no intermediate arrays are ever created, filter is called three
+   * times, and map is only called once:
+   *
+   * ```js
+   * oddSquares.get(1); // 9
+   * ```
+   *
+   * Any collection can be converted to a lazy Seq with `Seq()`.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { Map } = require('immutable')
+   * const map = Map({ a: 1, b: 2, c: 3 })
+   * const lazySeq = Seq(map)
+   * ```
+   *
+   * `Seq` allows for the efficient chaining of operations, allowing for the
+   * expression of logic that can otherwise be very tedious:
+   *
+   * ```js
+   * lazySeq
+   *   .flip()
+   *   .map(key => key.toUpperCase())
+   *   .flip()
+   * // Seq { A: 1, B: 1, C: 1 }
+   * ```
+   *
+   * As well as expressing logic that would otherwise seem memory or time
+   * limited, for example `Range` is a special kind of Lazy sequence.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { Range } = require('immutable')
+   * Range(1, Infinity)
+   *   .skip(1000)
+   *   .map(n => -n)
+   *   .filter(n => n % 2 === 0)
+   *   .take(2)
+   *   .reduce((r, n) => r * n, 1)
+   * // 1006008
+   * ```
+   *
+   * Seq is often used to provide a rich collection API to JavaScript Object.
+   *
+   * ```js
+   * Seq({ x: 0, y: 1, z: 2 }).map(v => v * 2).toObject();
+   * // { x: 0, y: 2, z: 4 }
+   * ```
+   */
+
+  namespace Seq {
+    /**
+     * True if `maybeSeq` is a Seq, it is not backed by a concrete
+     * structure such as Map, List, or Set.
+     */
+    function isSeq(
+      maybeSeq: unknown
+    ): maybeSeq is
+      | Seq.Indexed<unknown>
+      | Seq.Keyed<unknown, unknown>
+      | Seq.Set<unknown>;
+
+    /**
+     * `Seq` which represents key-value pairs.
+     */
+    namespace Keyed {}
+
+    /**
+     * Always returns a Seq.Keyed, if input is not keyed, expects an
+     * collection of [K, V] tuples.
+     *
+     * Note: `Seq.Keyed` is a conversion function and not a class, and does not
+     * use the `new` keyword during construction.
+     */
+    function Keyed<K, V>(collection?: Iterable<[K, V]>): Seq.Keyed<K, V>;
+    function Keyed<V>(obj: { [key: string]: V }): Seq.Keyed<string, V>;
+
+    interface Keyed<K, V> extends Seq<K, V>, Collection.Keyed<K, V> {
+      /**
+       * Deeply converts this Keyed Seq to equivalent native JavaScript Object.
+       *
+       * Converts keys to Strings.
+       */
+      toJS(): { [key in string | number | symbol]: DeepCopy<V> };
+
+      /**
+       * Shallowly converts this Keyed Seq to equivalent native JavaScript Object.
+       *
+       * Converts keys to Strings.
+       */
+      toJSON(): { [key in string | number | symbol]: V };
+
+      /**
+       * Shallowly converts this collection to an Array.
+       */
+      toArray(): Array<[K, V]>;
+
+      /**
+       * Returns itself
+       */
+      toSeq(): this;
+
+      /**
+       * Returns a new Seq with other collections concatenated to this one.
+       *
+       * All entries will be present in the resulting Seq, even if they
+       * have the same key.
+       */
+      concat<KC, VC>(
+        ...collections: Array<Iterable<[KC, VC]>>
+      ): Seq.Keyed<K | KC, V | VC>;
+      concat<C>(
+        ...collections: Array<{ [key: string]: C }>
+      ): Seq.Keyed<K | string, V | C>;
+
+      /**
+       * Returns a new Seq.Keyed with values passed through a
+       * `mapper` function.
+       *
+       * ```js
+       * const { Seq } = require('immutable')
+       * Seq.Keyed({ a: 1, b: 2 }).map(x => 10 * x)
+       * // Seq { "a": 10, "b": 20 }
+       * ```
+       *
+       * Note: `map()` always returns a new instance, even if it produced the
+       * same value at every step.
+       */
+      map<M>(
+        mapper: (value: V, key: K, iter: this) => M,
+        context?: unknown
+      ): Seq.Keyed<K, M>;
+
+      /**
+       * @see Collection.Keyed.mapKeys
+       */
+      mapKeys<M>(
+        mapper: (key: K, value: V, iter: this) => M,
+        context?: unknown
+      ): Seq.Keyed<M, V>;
+
+      /**
+       * @see Collection.Keyed.mapEntries
+       */
+      mapEntries<KM, VM>(
+        mapper: (
+          entry: [K, V],
+          index: number,
+          iter: this
+        ) => [KM, VM] | undefined,
+        context?: unknown
+      ): Seq.Keyed<KM, VM>;
+
+      /**
+       * Flat-maps the Seq, returning a Seq of the same type.
+       *
+       * Similar to `seq.map(...).flatten(true)`.
+       */
+      flatMap<KM, VM>(
+        mapper: (value: V, key: K, iter: this) => Iterable<[KM, VM]>,
+        context?: unknown
+      ): Seq.Keyed<KM, VM>;
+
+      /**
+       * Returns a new Seq with only the entries for which the `predicate`
+       * function returns true.
+       *
+       * Note: `filter()` always returns a new instance, even if it results in
+       * not filtering out any values.
+       */
+      filter<F extends V>(
+        predicate: (value: V, key: K, iter: this) => value is F,
+        context?: unknown
+      ): Seq.Keyed<K, F>;
+      filter(
+        predicate: (value: V, key: K, iter: this) => unknown,
+        context?: unknown
+      ): this;
+
+      /**
+       * Returns a new keyed Seq with the values for which the `predicate`
+       * function returns false and another for which is returns true.
+       */
+      partition<F extends V, C>(
+        predicate: (this: C, value: V, key: K, iter: this) => value is F,
+        context?: C
+      ): [Seq.Keyed<K, V>, Seq.Keyed<K, F>];
+      partition<C>(
+        predicate: (this: C, value: V, key: K, iter: this) => unknown,
+        context?: C
+      ): [this, this];
+
+      /**
+       * @see Collection.Keyed.flip
+       */
+      flip(): Seq.Keyed<V, K>;
+
+      [Symbol.iterator](): IterableIterator<[K, V]>;
+    }
+
+    /**
+     * `Seq` which represents an ordered indexed list of values.
+     */
+    namespace Indexed {
+      /**
+       * Provides an Seq.Indexed of the values provided.
+       */
+      function of<T>(...values: Array<T>): Seq.Indexed<T>;
+    }
+
+    /**
+     * Always returns Seq.Indexed, discarding associated keys and
+     * supplying incrementing indices.
+     *
+     * Note: `Seq.Indexed` is a conversion function and not a class, and does
+     * not use the `new` keyword during construction.
+     */
+    function Indexed<T>(
+      collection?: Iterable<T> | ArrayLike<T>
+    ): Seq.Indexed<T>;
+
+    interface Indexed<T> extends Seq<number, T>, Collection.Indexed<T> {
+      /**
+       * Deeply converts this Indexed Seq to equivalent native JavaScript Array.
+       */
+      toJS(): Array<DeepCopy<T>>;
+
+      /**
+       * Shallowly converts this Indexed Seq to equivalent native JavaScript Array.
+       */
+      toJSON(): Array<T>;
+
+      /**
+       * Shallowly converts this collection to an Array.
+       */
+      toArray(): Array<T>;
+
+      /**
+       * Returns itself
+       */
+      toSeq(): this;
+
+      /**
+       * Returns a new Seq with other collections concatenated to this one.
+       */
+      concat<C>(
+        ...valuesOrCollections: Array<Iterable<C> | C>
+      ): Seq.Indexed<T | C>;
+
+      /**
+       * Returns a new Seq.Indexed with values passed through a
+       * `mapper` function.
+       *
+       * ```js
+       * const { Seq } = require('immutable')
+       * Seq.Indexed([ 1, 2 ]).map(x => 10 * x)
+       * // Seq [ 10, 20 ]
+       * ```
+       *
+       * Note: `map()` always returns a new instance, even if it produced the
+       * same value at every step.
+       */
+      map<M>(
+        mapper: (value: T, key: number, iter: this) => M,
+        context?: unknown
+      ): Seq.Indexed<M>;
+
+      /**
+       * Flat-maps the Seq, returning a a Seq of the same type.
+       *
+       * Similar to `seq.map(...).flatten(true)`.
+       */
+      flatMap<M>(
+        mapper: (value: T, key: number, iter: this) => Iterable<M>,
+        context?: unknown
+      ): Seq.Indexed<M>;
+
+      /**
+       * Returns a new Seq with only the values for which the `predicate`
+       * function returns true.
+       *
+       * Note: `filter()` always returns a new instance, even if it results in
+       * not filtering out any values.
+       */
+      filter<F extends T>(
+        predicate: (value: T, index: number, iter: this) => value is F,
+        context?: unknown
+      ): Seq.Indexed<F>;
+      filter(
+        predicate: (value: T, index: number, iter: this) => unknown,
+        context?: unknown
+      ): this;
+
+      /**
+       * Returns a new indexed Seq with the values for which the `predicate`
+       * function returns false and another for which is returns true.
+       */
+      partition<F extends T, C>(
+        predicate: (this: C, value: T, index: number, iter: this) => value is F,
+        context?: C
+      ): [Seq.Indexed<T>, Seq.Indexed<F>];
+      partition<C>(
+        predicate: (this: C, value: T, index: number, iter: this) => unknown,
+        context?: C
+      ): [this, this];
+
+      /**
+       * Returns a Seq "zipped" with the provided collections.
+       *
+       * Like `zipWith`, but using the default `zipper`: creating an `Array`.
+       *
+       * ```js
+       * const a = Seq([ 1, 2, 3 ]);
+       * const b = Seq([ 4, 5, 6 ]);
+       * const c = a.zip(b); // Seq [ [ 1, 4 ], [ 2, 5 ], [ 3, 6 ] ]
+       * ```
+       */
+      zip<U>(other: Collection<unknown, U>): Seq.Indexed<[T, U]>;
+      zip<U, V>(
+        other: Collection<unknown, U>,
+        other2: Collection<unknown, V>
+      ): Seq.Indexed<[T, U, V]>;
+      zip(
+        ...collections: Array<Collection<unknown, unknown>>
+      ): Seq.Indexed<unknown>;
+
+      /**
+       * Returns a Seq "zipped" with the provided collections.
+       *
+       * Unlike `zip`, `zipAll` continues zipping until the longest collection is
+       * exhausted. Missing values from shorter collections are filled with `undefined`.
+       *
+       * ```js
+       * const a = Seq([ 1, 2 ]);
+       * const b = Seq([ 3, 4, 5 ]);
+       * const c = a.zipAll(b); // Seq [ [ 1, 3 ], [ 2, 4 ], [ undefined, 5 ] ]
+       * ```
+       */
+      zipAll<U>(other: Collection<unknown, U>): Seq.Indexed<[T, U]>;
+      zipAll<U, V>(
+        other: Collection<unknown, U>,
+        other2: Collection<unknown, V>
+      ): Seq.Indexed<[T, U, V]>;
+      zipAll(
+        ...collections: Array<Collection<unknown, unknown>>
+      ): Seq.Indexed<unknown>;
+
+      /**
+       * Returns a Seq "zipped" with the provided collections by using a
+       * custom `zipper` function.
+       *
+       * ```js
+       * const a = Seq([ 1, 2, 3 ]);
+       * const b = Seq([ 4, 5, 6 ]);
+       * const c = a.zipWith((a, b) => a + b, b);
+       * // Seq [ 5, 7, 9 ]
+       * ```
+       */
+      zipWith<U, Z>(
+        zipper: (value: T, otherValue: U) => Z,
+        otherCollection: Collection<unknown, U>
+      ): Seq.Indexed<Z>;
+      zipWith<U, V, Z>(
+        zipper: (value: T, otherValue: U, thirdValue: V) => Z,
+        otherCollection: Collection<unknown, U>,
+        thirdCollection: Collection<unknown, V>
+      ): Seq.Indexed<Z>;
+      zipWith<Z>(
+        zipper: (...values: Array<unknown>) => Z,
+        ...collections: Array<Collection<unknown, unknown>>
+      ): Seq.Indexed<Z>;
+
+      [Symbol.iterator](): IterableIterator<T>;
+    }
+
+    /**
+     * `Seq` which represents a set of values.
+     *
+     * Because `Seq` are often lazy, `Seq.Set` does not provide the same guarantee
+     * of value uniqueness as the concrete `Set`.
+     */
+    namespace Set {
+      /**
+       * Returns a Seq.Set of the provided values
+       */
+      function of<T>(...values: Array<T>): Seq.Set<T>;
+    }
+
+    /**
+     * Always returns a Seq.Set, discarding associated indices or keys.
+     *
+     * Note: `Seq.Set` is a conversion function and not a class, and does not
+     * use the `new` keyword during construction.
+     */
+    function Set<T>(collection?: Iterable<T> | ArrayLike<T>): Seq.Set<T>;
+
+    interface Set<T> extends Seq<T, T>, Collection.Set<T> {
+      /**
+       * Deeply converts this Set Seq to equivalent native JavaScript Array.
+       */
+      toJS(): Array<DeepCopy<T>>;
+
+      /**
+       * Shallowly converts this Set Seq to equivalent native JavaScript Array.
+       */
+      toJSON(): Array<T>;
+
+      /**
+       * Shallowly converts this collection to an Array.
+       */
+      toArray(): Array<T>;
+
+      /**
+       * Returns itself
+       */
+      toSeq(): this;
+
+      /**
+       * Returns a new Seq with other collections concatenated to this one.
+       *
+       * All entries will be present in the resulting Seq, even if they
+       * are duplicates.
+       */
+      concat<U>(...collections: Array<Iterable<U>>): Seq.Set<T | U>;
+
+      /**
+       * Returns a new Seq.Set with values passed through a
+       * `mapper` function.
+       *
+       * ```js
+       * Seq.Set([ 1, 2 ]).map(x => 10 * x)
+       * // Seq { 10, 20 }
+       * ```
+       *
+       * Note: `map()` always returns a new instance, even if it produced the
+       * same value at every step.
+       */
+      map<M>(
+        mapper: (value: T, key: T, iter: this) => M,
+        context?: unknown
+      ): Seq.Set<M>;
+
+      /**
+       * Flat-maps the Seq, returning a Seq of the same type.
+       *
+       * Similar to `seq.map(...).flatten(true)`.
+       */
+      flatMap<M>(
+        mapper: (value: T, key: T, iter: this) => Iterable<M>,
+        context?: unknown
+      ): Seq.Set<M>;
+
+      /**
+       * Returns a new Seq with only the values for which the `predicate`
+       * function returns true.
+       *
+       * Note: `filter()` always returns a new instance, even if it results in
+       * not filtering out any values.
+       */
+      filter<F extends T>(
+        predicate: (value: T, key: T, iter: this) => value is F,
+        context?: unknown
+      ): Seq.Set<F>;
+      filter(
+        predicate: (value: T, key: T, iter: this) => unknown,
+        context?: unknown
+      ): this;
+
+      /**
+       * Returns a new set Seq with the values for which the `predicate`
+       * function returns false and another for which is returns true.
+       */
+      partition<F extends T, C>(
+        predicate: (this: C, value: T, key: T, iter: this) => value is F,
+        context?: C
+      ): [Seq.Set<T>, Seq.Set<F>];
+      partition<C>(
+        predicate: (this: C, value: T, key: T, iter: this) => unknown,
+        context?: C
+      ): [this, this];
+
+      [Symbol.iterator](): IterableIterator<T>;
+    }
+  }
+
+  /**
+   * Creates a Seq.
+   *
+   * Returns a particular kind of `Seq` based on the input.
+   *
+   *   * If a `Seq`, that same `Seq`.
+   *   * If an `Collection`, a `Seq` of the same kind (Keyed, Indexed, or Set).
+   *   * If an Array-like, an `Seq.Indexed`.
+   *   * If an Iterable Object, an `Seq.Indexed`.
+   *   * If an Object, a `Seq.Keyed`.
+   *
+   * Note: An Iterator itself will be treated as an object, becoming a `Seq.Keyed`,
+   * which is usually not what you want. You should turn your Iterator Object into
+   * an iterable object by defining a Symbol.iterator (or @@iterator) method which
+   * returns `this`.
+   *
+   * Note: `Seq` is a conversion function and not a class, and does not use the
+   * `new` keyword during construction.
+   */
+  function Seq<S extends Seq<unknown, unknown>>(seq: S): S;
+  function Seq<K, V>(collection: Collection.Keyed<K, V>): Seq.Keyed<K, V>;
+  function Seq<T>(collection: Collection.Set<T>): Seq.Set<T>;
+  function Seq<T>(
+    collection: Collection.Indexed<T> | Iterable<T> | ArrayLike<T>
+  ): Seq.Indexed<T>;
+  function Seq<V>(obj: { [key: string]: V }): Seq.Keyed<string, V>;
+  function Seq<K = unknown, V = unknown>(): Seq<K, V>;
+
+  interface Seq<K, V> extends Collection<K, V> {
+    /**
+     * Some Seqs can describe their size lazily. When this is the case,
+     * size will be an integer. Otherwise it will be undefined.
+     *
+     * For example, Seqs returned from `map()` or `reverse()`
+     * preserve the size of the original `Seq` while `filter()` does not.
+     *
+     * Note: `Range`, `Repeat` and `Seq`s made from `Array`s and `Object`s will
+     * always have a size.
+     */
+    readonly size: number | undefined;
+
+    // Force evaluation
+
+    /**
+     * Because Sequences are lazy and designed to be chained together, they do
+     * not cache their results. For example, this map function is called a total
+     * of 6 times, as each `join` iterates the Seq of three values.
+     *
+     *     var squares = Seq([ 1, 2, 3 ]).map(x => x * x)
+     *     squares.join() + squares.join()
+     *
+     * If you know a `Seq` will be used multiple times, it may be more
+     * efficient to first cache it in memory. Here, the map function is called
+     * only 3 times.
+     *
+     *     var squares = Seq([ 1, 2, 3 ]).map(x => x * x).cacheResult()
+     *     squares.join() + squares.join()
+     *
+     * Use this method judiciously, as it must fully evaluate a Seq which can be
+     * a burden on memory and possibly performance.
+     *
+     * Note: after calling `cacheResult`, a Seq will always have a `size`.
+     */
+    cacheResult(): this;
+
+    // Sequence algorithms
+
+    /**
+     * Returns a new Seq with values passed through a
+     * `mapper` function.
+     *
+     * ```js
+     * const { Seq } = require('immutable')
+     * Seq([ 1, 2 ]).map(x => 10 * x)
+     * // Seq [ 10, 20 ]
+     * ```
+     *
+     * Note: `map()` always returns a new instance, even if it produced the same
+     * value at every step.
+     */
+    map<M>(
+      mapper: (value: V, key: K, iter: this) => M,
+      context?: unknown
+    ): Seq<K, M>;
+
+    /**
+     * Returns a new Seq with values passed through a
+     * `mapper` function.
+     *
+     * ```js
+     * const { Seq } = require('immutable')
+     * Seq([ 1, 2 ]).map(x => 10 * x)
+     * // Seq [ 10, 20 ]
+     * ```
+     *
+     * Note: `map()` always returns a new instance, even if it produced the same
+     * value at every step.
+     * Note: used only for sets.
+     */
+    map<M>(
+      mapper: (value: V, key: K, iter: this) => M,
+      context?: unknown
+    ): Seq<M, M>;
+
+    /**
+     * Flat-maps the Seq, returning a Seq of the same type.
+     *
+     * Similar to `seq.map(...).flatten(true)`.
+     */
+    flatMap<M>(
+      mapper: (value: V, key: K, iter: this) => Iterable<M>,
+      context?: unknown
+    ): Seq<K, M>;
+
+    /**
+     * Flat-maps the Seq, returning a Seq of the same type.
+     *
+     * Similar to `seq.map(...).flatten(true)`.
+     * Note: Used only for sets.
+     */
+    flatMap<M>(
+      mapper: (value: V, key: K, iter: this) => Iterable<M>,
+      context?: unknown
+    ): Seq<M, M>;
+
+    /**
+     * Returns a new Seq with only the values for which the `predicate`
+     * function returns true.
+     *
+     * Note: `filter()` always returns a new instance, even if it results in
+     * not filtering out any values.
+     */
+    filter<F extends V>(
+      predicate: (value: V, key: K, iter: this) => value is F,
+      context?: unknown
+    ): Seq<K, F>;
+    filter(
+      predicate: (value: V, key: K, iter: this) => unknown,
+      context?: unknown
+    ): this;
+
+    /**
+     * Returns a new Seq with the values for which the `predicate` function
+     * returns false and another for which is returns true.
+     */
+    partition<F extends V, C>(
+      predicate: (this: C, value: V, key: K, iter: this) => value is F,
+      context?: C
+    ): [Seq<K, V>, Seq<K, F>];
+    partition<C>(
+      predicate: (this: C, value: V, key: K, iter: this) => unknown,
+      context?: C
+    ): [this, this];
+  }
+
+  /**
+   * The `Collection` is a set of (key, value) entries which can be iterated, and
+   * is the base class for all collections in `immutable`, allowing them to
+   * make use of all the Collection methods (such as `map` and `filter`).
+   *
+   * Note: A collection is always iterated in the same order, however that order
+   * may not always be well defined, as is the case for the `Map` and `Set`.
+   *
+   * Collection is the abstract base class for concrete data structures. It
+   * cannot be constructed directly.
+   *
+   * Implementations should extend one of the subclasses, `Collection.Keyed`,
+   * `Collection.Indexed`, or `Collection.Set`.
+   */
+  namespace Collection {
+    /**
+     * Keyed Collections have discrete keys tied to each value.
+     *
+     * When iterating `Collection.Keyed`, each iteration will yield a `[K, V]`
+     * tuple, in other words, `Collection#entries` is the default iterator for
+     * Keyed Collections.
+     */
+    namespace Keyed {}
+
+    /**
+     * Creates a Collection.Keyed
+     *
+     * Similar to `Collection()`, however it expects collection-likes of [K, V]
+     * tuples if not constructed from a Collection.Keyed or JS Object.
+     *
+     * Note: `Collection.Keyed` is a conversion function and not a class, and
+     * does not use the `new` keyword during construction.
+     */
+    function Keyed<K, V>(collection?: Iterable<[K, V]>): Collection.Keyed<K, V>;
+    function Keyed<V>(obj: { [key: string]: V }): Collection.Keyed<string, V>;
+
+    interface Keyed<K, V> extends Collection<K, V> {
+      /**
+       * Deeply converts this Keyed collection to equivalent native JavaScript Object.
+       *
+       * Converts keys to Strings.
+       */
+      toJS(): { [key in string | number | symbol]: DeepCopy<V> };
+
+      /**
+       * Shallowly converts this Keyed collection to equivalent native JavaScript Object.
+       *
+       * Converts keys to Strings.
+       */
+      toJSON(): { [key in string | number | symbol]: V };
+
+      /**
+       * Shallowly converts this collection to an Array.
+       */
+      toArray(): Array<[K, V]>;
+
+      /**
+       * Returns Seq.Keyed.
+       * @override
+       */
+      toSeq(): Seq.Keyed<K, V>;
+
+      // Sequence functions
+
+      /**
+       * Returns a new Collection.Keyed of the same type where the keys and values
+       * have been flipped.
+       *
+       * <!-- runkit:activate -->
+       * ```js
+       * const { Map } = require('immutable')
+       * Map({ a: 'z', b: 'y' }).flip()
+       * // Map { "z": "a", "y": "b" }
+       * ```
+       */
+      flip(): Collection.Keyed<V, K>;
+
+      /**
+       * Returns a new Collection with other collections concatenated to this one.
+       */
+      concat<KC, VC>(
+        ...collections: Array<Iterable<[KC, VC]>>
+      ): Collection.Keyed<K | KC, V | VC>;
+      concat<C>(
+        ...collections: Array<{ [key: string]: C }>
+      ): Collection.Keyed<K | string, V | C>;
+
+      /**
+       * Returns a new Collection.Keyed with values passed through a
+       * `mapper` function.
+       *
+       * ```js
+       * const { Collection } = require('immutable')
+       * Collection.Keyed({ a: 1, b: 2 }).map(x => 10 * x)
+       * // Seq { "a": 10, "b": 20 }
+       * ```
+       *
+       * Note: `map()` always returns a new instance, even if it produced the
+       * same value at every step.
+       */
+      map<M>(
+        mapper: (value: V, key: K, iter: this) => M,
+        context?: unknown
+      ): Collection.Keyed<K, M>;
+
+      /**
+       * Returns a new Collection.Keyed of the same type with keys passed through
+       * a `mapper` function.
+       *
+       * <!-- runkit:activate -->
+       * ```js
+       * const { Map } = require('immutable')
+       * Map({ a: 1, b: 2 }).mapKeys(x => x.toUpperCase())
+       * // Map { "A": 1, "B": 2 }
+       * ```
+       *
+       * Note: `mapKeys()` always returns a new instance, even if it produced
+       * the same key at every step.
+       */
+      mapKeys<M>(
+        mapper: (key: K, value: V, iter: this) => M,
+        context?: unknown
+      ): Collection.Keyed<M, V>;
+
+      /**
+       * Returns a new Collection.Keyed of the same type with entries
+       * ([key, value] tuples) passed through a `mapper` function.
+       *
+       * <!-- runkit:activate -->
+       * ```js
+       * const { Map } = require('immutable')
+       * Map({ a: 1, b: 2 })
+       *   .mapEntries(([ k, v ]) => [ k.toUpperCase(), v * 2 ])
+       * // Map { "A": 2, "B": 4 }
+       * ```
+       *
+       * Note: `mapEntries()` always returns a new instance, even if it produced
+       * the same entry at every step.
+       *
+       * If the mapper function returns `undefined`, then the entry will be filtered
+       */
+      mapEntries<KM, VM>(
+        mapper: (
+          entry: [K, V],
+          index: number,
+          iter: this
+        ) => [KM, VM] | undefined,
+        context?: unknown
+      ): Collection.Keyed<KM, VM>;
+
+      /**
+       * Flat-maps the Collection, returning a Collection of the same type.
+       *
+       * Similar to `collection.map(...).flatten(true)`.
+       */
+      flatMap<KM, VM>(
+        mapper: (value: V, key: K, iter: this) => Iterable<[KM, VM]>,
+        context?: unknown
+      ): Collection.Keyed<KM, VM>;
+
+      /**
+       * Returns a new Collection with only the values for which the `predicate`
+       * function returns true.
+       *
+       * Note: `filter()` always returns a new instance, even if it results in
+       * not filtering out any values.
+       */
+      filter<F extends V>(
+        predicate: (value: V, key: K, iter: this) => value is F,
+        context?: unknown
+      ): Collection.Keyed<K, F>;
+      filter(
+        predicate: (value: V, key: K, iter: this) => unknown,
+        context?: unknown
+      ): this;
+
+      /**
+       * Returns a new keyed Collection with the values for which the
+       * `predicate` function returns false and another for which is returns
+       * true.
+       */
+      partition<F extends V, C>(
+        predicate: (this: C, value: V, key: K, iter: this) => value is F,
+        context?: C
+      ): [Collection.Keyed<K, V>, Collection.Keyed<K, F>];
+      partition<C>(
+        predicate: (this: C, value: V, key: K, iter: this) => unknown,
+        context?: C
+      ): [this, this];
+
+      [Symbol.iterator](): IterableIterator<[K, V]>;
+    }
+
+    /**
+     * Indexed Collections have incrementing numeric keys. They exhibit
+     * slightly different behavior than `Collection.Keyed` for some methods in order
+     * to better mirror the behavior of JavaScript's `Array`, and add methods
+     * which do not make sense on non-indexed Collections such as `indexOf`.
+     *
+     * Unlike JavaScript arrays, `Collection.Indexed`s are always dense. "Unset"
+     * indices and `undefined` indices are indistinguishable, and all indices from
+     * 0 to `size` are visited when iterated.
+     *
+     * All Collection.Indexed methods return re-indexed Collections. In other words,
+     * indices always start at 0 and increment until size. If you wish to
+     * preserve indices, using them as keys, convert to a Collection.Keyed by
+     * calling `toKeyedSeq`.
+     */
+    namespace Indexed {}
+
+    /**
+     * Creates a new Collection.Indexed.
+     *
+     * Note: `Collection.Indexed` is a conversion function and not a class, and
+     * does not use the `new` keyword during construction.
+     */
+    function Indexed<T>(
+      collection?: Iterable<T> | ArrayLike<T>
+    ): Collection.Indexed<T>;
+
+    interface Indexed<T> extends Collection<number, T> {
+      /**
+       * Deeply converts this Indexed collection to equivalent native JavaScript Array.
+       */
+      toJS(): Array<DeepCopy<T>>;
+
+      /**
+       * Shallowly converts this Indexed collection to equivalent native JavaScript Array.
+       */
+      toJSON(): Array<T>;
+
+      /**
+       * Shallowly converts this collection to an Array.
+       */
+      toArray(): Array<T>;
+
+      // Reading values
+
+      /**
+       * Returns the value associated with the provided index, or notSetValue if
+       * the index is beyond the bounds of the Collection.
+       *
+       * `index` may be a negative number, which indexes back from the end of the
+       * Collection. `s.get(-1)` gets the last item in the Collection.
+       */
+      get<NSV>(index: number, notSetValue: NSV): T | NSV;
+      get(index: number): T | undefined;
+
+      // Conversion to Seq
+
+      /**
+       * Returns Seq.Indexed.
+       * @override
+       */
+      toSeq(): Seq.Indexed<T>;
+
+      /**
+       * If this is a collection of [key, value] entry tuples, it will return a
+       * Seq.Keyed of those entries.
+       */
+      fromEntrySeq(): Seq.Keyed<unknown, unknown>;
+
+      // Combination
+
+      /**
+       * Returns a Collection of the same type with `separator` between each item
+       * in this Collection.
+       */
+      interpose(separator: T): this;
+
+      /**
+       * Returns a Collection of the same type with the provided `collections`
+       * interleaved into this collection.
+       *
+       * The resulting Collection includes the first item from each, then the
+       * second from each, etc.
+       *
+       * <!-- runkit:activate
+       *      { "preamble": "require('immutable')"}
+       * -->
+       * ```js
+       * const { List } = require('immutable')
+       * List([ 1, 2, 3 ]).interleave(List([ 'A', 'B', 'C' ]))
+       * // List [ 1, "A", 2, "B", 3, "C" ]
+       * ```
+       *
+       * The shortest Collection stops interleave.
+       *
+       * <!-- runkit:activate
+       *      { "preamble": "const { List } = require('immutable')" }
+       * -->
+       * ```js
+       * List([ 1, 2, 3 ]).interleave(
+       *   List([ 'A', 'B' ]),
+       *   List([ 'X', 'Y', 'Z' ])
+       * )
+       * // List [ 1, "A", "X", 2, "B", "Y" ]
+       * ```
+       *
+       * Since `interleave()` re-indexes values, it produces a complete copy,
+       * which has `O(N)` complexity.
+       *
+       * Note: `interleave` *cannot* be used in `withMutations`.
+       */
+      interleave(...collections: Array<Collection<unknown, T>>): this;
+
+      /**
+       * Splice returns a new indexed Collection by replacing a region of this
+       * Collection with new values. If values are not provided, it only skips the
+       * region to be removed.
+       *
+       * `index` may be a negative number, which indexes back from the end of the
+       * Collection. `s.splice(-2)` splices after the second to last item.
+       *
+       * <!-- runkit:activate -->
+       * ```js
+       * const { List } = require('immutable')
+       * List([ 'a', 'b', 'c', 'd' ]).splice(1, 2, 'q', 'r', 's')
+       * // List [ "a", "q", "r", "s", "d" ]
+       * ```
+       *
+       * Since `splice()` re-indexes values, it produces a complete copy, which
+       * has `O(N)` complexity.
+       *
+       * Note: `splice` *cannot* be used in `withMutations`.
+       */
+      splice(index: number, removeNum: number, ...values: Array<T>): this;
+
+      /**
+       * Returns a Collection of the same type "zipped" with the provided
+       * collections.
+       *
+       * Like `zipWith`, but using the default `zipper`: creating an `Array`.
+       *
+       *
+       * <!-- runkit:activate
+       *      { "preamble": "const { List } = require('immutable')" }
+       * -->
+       * ```js
+       * const a = List([ 1, 2, 3 ]);
+       * const b = List([ 4, 5, 6 ]);
+       * const c = a.zip(b); // List [ [ 1, 4 ], [ 2, 5 ], [ 3, 6 ] ]
+       * ```
+       */
+      zip<U>(other: Collection<unknown, U>): Collection.Indexed<[T, U]>;
+      zip<U, V>(
+        other: Collection<unknown, U>,
+        other2: Collection<unknown, V>
+      ): Collection.Indexed<[T, U, V]>;
+      zip(
+        ...collections: Array<Collection<unknown, unknown>>
+      ): Collection.Indexed<unknown>;
+
+      /**
+       * Returns a Collection "zipped" with the provided collections.
+       *
+       * Unlike `zip`, `zipAll` continues zipping until the longest collection is
+       * exhausted. Missing values from shorter collections are filled with `undefined`.
+       *
+       * ```js
+       * const a = List([ 1, 2 ]);
+       * const b = List([ 3, 4, 5 ]);
+       * const c = a.zipAll(b); // List [ [ 1, 3 ], [ 2, 4 ], [ undefined, 5 ] ]
+       * ```
+       */
+      zipAll<U>(other: Collection<unknown, U>): Collection.Indexed<[T, U]>;
+      zipAll<U, V>(
+        other: Collection<unknown, U>,
+        other2: Collection<unknown, V>
+      ): Collection.Indexed<[T, U, V]>;
+      zipAll(
+        ...collections: Array<Collection<unknown, unknown>>
+      ): Collection.Indexed<unknown>;
+
+      /**
+       * Returns a Collection of the same type "zipped" with the provided
+       * collections by using a custom `zipper` function.
+       *
+       * <!-- runkit:activate
+       *      { "preamble": "const { List } = require('immutable')" }
+       * -->
+       * ```js
+       * const a = List([ 1, 2, 3 ]);
+       * const b = List([ 4, 5, 6 ]);
+       * const c = a.zipWith((a, b) => a + b, b);
+       * // List [ 5, 7, 9 ]
+       * ```
+       */
+      zipWith<U, Z>(
+        zipper: (value: T, otherValue: U) => Z,
+        otherCollection: Collection<unknown, U>
+      ): Collection.Indexed<Z>;
+      zipWith<U, V, Z>(
+        zipper: (value: T, otherValue: U, thirdValue: V) => Z,
+        otherCollection: Collection<unknown, U>,
+        thirdCollection: Collection<unknown, V>
+      ): Collection.Indexed<Z>;
+      zipWith<Z>(
+        zipper: (...values: Array<unknown>) => Z,
+        ...collections: Array<Collection<unknown, unknown>>
+      ): Collection.Indexed<Z>;
+
+      // Search for value
+
+      /**
+       * Returns the first index at which a given value can be found in the
+       * Collection, or -1 if it is not present.
+       */
+      indexOf(searchValue: T): number;
+
+      /**
+       * Returns the last index at which a given value can be found in the
+       * Collection, or -1 if it is not present.
+       */
+      lastIndexOf(searchValue: T): number;
+
+      /**
+       * Returns the first index in the Collection where a value satisfies the
+       * provided predicate function. Otherwise -1 is returned.
+       */
+      findIndex(
+        predicate: (value: T, index: number, iter: this) => boolean,
+        context?: unknown
+      ): number;
+
+      /**
+       * Returns the last index in the Collection where a value satisfies the
+       * provided predicate function. Otherwise -1 is returned.
+       */
+      findLastIndex(
+        predicate: (value: T, index: number, iter: this) => boolean,
+        context?: unknown
+      ): number;
+
+      // Sequence algorithms
+
+      /**
+       * Returns a new Collection with other collections concatenated to this one.
+       */
+      concat<C>(
+        ...valuesOrCollections: Array<Iterable<C> | C>
+      ): Collection.Indexed<T | C>;
+
+      /**
+       * Returns a new Collection.Indexed with values passed through a
+       * `mapper` function.
+       *
+       * ```js
+       * const { Collection } = require('immutable')
+       * Collection.Indexed([1,2]).map(x => 10 * x)
+       * // Seq [ 1, 2 ]
+       * ```
+       *
+       * Note: `map()` always returns a new instance, even if it produced the
+       * same value at every step.
+       */
+      map<M>(
+        mapper: (value: T, key: number, iter: this) => M,
+        context?: unknown
+      ): Collection.Indexed<M>;
+
+      /**
+       * Flat-maps the Collection, returning a Collection of the same type.
+       *
+       * Similar to `collection.map(...).flatten(true)`.
+       */
+      flatMap<M>(
+        mapper: (value: T, key: number, iter: this) => Iterable<M>,
+        context?: unknown
+      ): Collection.Indexed<M>;
+
+      /**
+       * Returns a new Collection with only the values for which the `predicate`
+       * function returns true.
+       *
+       * Note: `filter()` always returns a new instance, even if it results in
+       * not filtering out any values.
+       */
+      filter<F extends T>(
+        predicate: (value: T, index: number, iter: this) => value is F,
+        context?: unknown
+      ): Collection.Indexed<F>;
+      filter(
+        predicate: (value: T, index: number, iter: this) => unknown,
+        context?: unknown
+      ): this;
+
+      /**
+       * Returns a new indexed Collection with the values for which the
+       * `predicate` function returns false and another for which is returns
+       * true.
+       */
+      partition<F extends T, C>(
+        predicate: (this: C, value: T, index: number, iter: this) => value is F,
+        context?: C
+      ): [Collection.Indexed<T>, Collection.Indexed<F>];
+      partition<C>(
+        predicate: (this: C, value: T, index: number, iter: this) => unknown,
+        context?: C
+      ): [this, this];
+
+      [Symbol.iterator](): IterableIterator<T>;
+    }
+
+    /**
+     * Set Collections only represent values. They have no associated keys or
+     * indices. Duplicate values are possible in the lazy `Seq.Set`s, however
+     * the concrete `Set` Collection does not allow duplicate values.
+     *
+     * Collection methods on Collection.Set such as `map` and `forEach` will provide
+     * the value as both the first and second arguments to the provided function.
+     *
+     * ```js
+     * const { Collection } = require('immutable')
+     * const seq = Collection.Set([ 'A', 'B', 'C' ])
+     * // Seq { "A", "B", "C" }
+     * seq.forEach((v, k) =>
+     *  assert.equal(v, k)
+     * )
+     * ```
+     */
+    namespace Set {}
+
+    /**
+     * Similar to `Collection()`, but always returns a Collection.Set.
+     *
+     * Note: `Collection.Set` is a factory function and not a class, and does
+     * not use the `new` keyword during construction.
+     */
+    function Set<T>(collection?: Iterable<T> | ArrayLike<T>): Collection.Set<T>;
+
+    interface Set<T> extends Collection<T, T> {
+      /**
+       * Deeply converts this Set collection to equivalent native JavaScript Array.
+       */
+      toJS(): Array<DeepCopy<T>>;
+
+      /**
+       * Shallowly converts this Set collection to equivalent native JavaScript Array.
+       */
+      toJSON(): Array<T>;
+
+      /**
+       * Shallowly converts this collection to an Array.
+       */
+      toArray(): Array<T>;
+
+      /**
+       * Returns Seq.Set.
+       * @override
+       */
+      toSeq(): Seq.Set<T>;
+
+      // Sequence algorithms
+
+      /**
+       * Returns a new Collection with other collections concatenated to this one.
+       */
+      concat<U>(...collections: Array<Iterable<U>>): Collection.Set<T | U>;
+
+      /**
+       * Returns a new Collection.Set with values passed through a
+       * `mapper` function.
+       *
+       * ```
+       * Collection.Set([ 1, 2 ]).map(x => 10 * x)
+       * // Seq { 1, 2 }
+       * ```
+       *
+       * Note: `map()` always returns a new instance, even if it produced the
+       * same value at every step.
+       */
+      map<M>(
+        mapper: (value: T, key: T, iter: this) => M,
+        context?: unknown
+      ): Collection.Set<M>;
+
+      /**
+       * Flat-maps the Collection, returning a Collection of the same type.
+       *
+       * Similar to `collection.map(...).flatten(true)`.
+       */
+      flatMap<M>(
+        mapper: (value: T, key: T, iter: this) => Iterable<M>,
+        context?: unknown
+      ): Collection.Set<M>;
+
+      /**
+       * Returns a new Collection with only the values for which the `predicate`
+       * function returns true.
+       *
+       * Note: `filter()` always returns a new instance, even if it results in
+       * not filtering out any values.
+       */
+      filter<F extends T>(
+        predicate: (value: T, key: T, iter: this) => value is F,
+        context?: unknown
+      ): Collection.Set<F>;
+      filter(
+        predicate: (value: T, key: T, iter: this) => unknown,
+        context?: unknown
+      ): this;
+
+      /**
+       * Returns a new set Collection with the values for which the
+       * `predicate` function returns false and another for which is returns
+       * true.
+       */
+      partition<F extends T, C>(
+        predicate: (this: C, value: T, key: T, iter: this) => value is F,
+        context?: C
+      ): [Collection.Set<T>, Collection.Set<F>];
+      partition<C>(
+        predicate: (this: C, value: T, key: T, iter: this) => unknown,
+        context?: C
+      ): [this, this];
+
+      [Symbol.iterator](): IterableIterator<T>;
+    }
+  }
+
+  /**
+   * Creates a Collection.
+   *
+   * The type of Collection created is based on the input.
+   *
+   *   * If an `Collection`, that same `Collection`.
+   *   * If an Array-like, an `Collection.Indexed`.
+   *   * If an Object with an Iterator defined, an `Collection.Indexed`.
+   *   * If an Object, an `Collection.Keyed`.
+   *
+   * This methods forces the conversion of Objects and Strings to Collections.
+   * If you want to ensure that a Collection of one item is returned, use
+   * `Seq.of`.
+   *
+   * Note: An Iterator itself will be treated as an object, becoming a `Seq.Keyed`,
+   * which is usually not what you want. You should turn your Iterator Object into
+   * an iterable object by defining a Symbol.iterator (or @@iterator) method which
+   * returns `this`.
+   *
+   * Note: `Collection` is a conversion function and not a class, and does not
+   * use the `new` keyword during construction.
+   */
+  function Collection<I extends Collection<unknown, unknown>>(collection: I): I;
+  function Collection<T>(
+    collection: Iterable<T> | ArrayLike<T>
+  ): Collection.Indexed<T>;
+  function Collection<V>(obj: {
+    [key: string]: V;
+  }): Collection.Keyed<string, V>;
+  function Collection<K = unknown, V = unknown>(): Collection<K, V>;
+
+  interface Collection<K, V> extends ValueObject {
+    // Value equality
+
+    /**
+     * True if this and the other Collection have value equality, as defined
+     * by `Immutable.is()`.
+     *
+     * Note: This is equivalent to `Immutable.is(this, other)`, but provided to
+     * allow for chained expressions.
+     */
+    equals(other: unknown): boolean;
+
+    /**
+     * Computes and returns the hashed identity for this Collection.
+     *
+     * The `hashCode` of a Collection is used to determine potential equality,
+     * and is used when adding this to a `Set` or as a key in a `Map`, enabling
+     * lookup via a different instance.
+     *
+     * <!-- runkit:activate
+     *      { "preamble": "const { Set,  List } = require('immutable')" }
+     * -->
+     * ```js
+     * const a = List([ 1, 2, 3 ]);
+     * const b = List([ 1, 2, 3 ]);
+     * assert.notStrictEqual(a, b); // different instances
+     * const set = Set([ a ]);
+     * assert.equal(set.has(b), true);
+     * ```
+     *
+     * If two values have the same `hashCode`, they are [not guaranteed
+     * to be equal][Hash Collision]. If two values have different `hashCode`s,
+     * they must not be equal.
+     *
+     * [Hash Collision]: https://en.wikipedia.org/wiki/Collision_(computer_science)
+     */
+    hashCode(): number;
+
+    // Reading values
+
+    /**
+     * Returns the value associated with the provided key, or notSetValue if
+     * the Collection does not contain this key.
+     *
+     * Note: it is possible a key may be associated with an `undefined` value,
+     * so if `notSetValue` is not provided and this method returns `undefined`,
+     * that does not guarantee the key was not found.
+     */
+    get<NSV>(key: K, notSetValue: NSV): V | NSV;
+    get(key: K): V | undefined;
+
+    /**
+     * True if a key exists within this `Collection`, using `Immutable.is`
+     * to determine equality
+     */
+    has(key: K): boolean;
+
+    /**
+     * True if a value exists within this `Collection`, using `Immutable.is`
+     * to determine equality
+     * @alias contains
+     */
+    includes(value: V): boolean;
+    contains(value: V): boolean;
+
+    /**
+     * In case the `Collection` is not empty returns the first element of the
+     * `Collection`.
+     * In case the `Collection` is empty returns the optional default
+     * value if provided, if no default value is provided returns undefined.
+     */
+    first<NSV>(notSetValue: NSV): V | NSV;
+    first(): V | undefined;
+
+    /**
+     * In case the `Collection` is not empty returns the last element of the
+     * `Collection`.
+     * In case the `Collection` is empty returns the optional default
+     * value if provided, if no default value is provided returns undefined.
+     */
+    last<NSV>(notSetValue: NSV): V | NSV;
+    last(): V | undefined;
+
+    // Reading deep values
+
+    /**
+     * Returns the value found by following a path of keys or indices through
+     * nested Collections.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map, List } = require('immutable')
+     * const deepData = Map({ x: List([ Map({ y: 123 }) ]) });
+     * deepData.getIn(['x', 0, 'y']) // 123
+     * ```
+     *
+     * Plain JavaScript Object or Arrays may be nested within an Immutable.js
+     * Collection, and getIn() can access those values as well:
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map, List } = require('immutable')
+     * const deepData = Map({ x: [ { y: 123 } ] });
+     * deepData.getIn(['x', 0, 'y']) // 123
+     * ```
+     */
+    getIn(searchKeyPath: Iterable<unknown>, notSetValue?: unknown): unknown;
+
+    /**
+     * True if the result of following a path of keys or indices through nested
+     * Collections results in a set value.
+     */
+    hasIn(searchKeyPath: Iterable<unknown>): boolean;
+
+    // Persistent changes
+
+    /**
+     * This can be very useful as a way to "chain" a normal function into a
+     * sequence of methods. RxJS calls this "let" and lodash calls it "thru".
+     *
+     * For example, to sum a Seq after mapping and filtering:
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Seq } = require('immutable')
+     *
+     * function sum(collection) {
+     *   return collection.reduce((sum, x) => sum + x, 0)
+     * }
+     *
+     * Seq([ 1, 2, 3 ])
+     *   .map(x => x + 1)
+     *   .filter(x => x % 2 === 0)
+     *   .update(sum)
+     * // 6
+     * ```
+     */
+    update<R>(updater: (value: this) => R): R;
+
+    // Conversion to JavaScript types
+
+    /**
+     * Deeply converts this Collection to equivalent native JavaScript Array or Object.
+     *
+     * `Collection.Indexed`, and `Collection.Set` become `Array`, while
+     * `Collection.Keyed` become `Object`, converting keys to Strings.
+     */
+    toJS():
+      | Array<DeepCopy<V>>
+      | { [key in string | number | symbol]: DeepCopy<V> };
+
+    /**
+     * Shallowly converts this Collection to equivalent native JavaScript Array or Object.
+     *
+     * `Collection.Indexed`, and `Collection.Set` become `Array`, while
+     * `Collection.Keyed` become `Object`, converting keys to Strings.
+     */
+    toJSON(): Array<V> | { [key in string | number | symbol]: V };
+
+    /**
+     * Shallowly converts this collection to an Array.
+     *
+     * `Collection.Indexed`, and `Collection.Set` produce an Array of values.
+     * `Collection.Keyed` produce an Array of [key, value] tuples.
+     */
+    toArray(): Array<V> | Array<[K, V]>;
+
+    /**
+     * Shallowly converts this Collection to an Object.
+     *
+     * Converts keys to Strings.
+     */
+    toObject(): { [key: string]: V };
+
+    // Conversion to Collections
+
+    /**
+     * Converts this Collection to a Map, Throws if keys are not hashable.
+     *
+     * Note: This is equivalent to `Map(this.toKeyedSeq())`, but provided
+     * for convenience and to allow for chained expressions.
+     */
+    toMap(): Map<K, V>;
+
+    /**
+     * Converts this Collection to a Map, maintaining the order of iteration.
+     *
+     * Note: This is equivalent to `OrderedMap(this.toKeyedSeq())`, but
+     * provided for convenience and to allow for chained expressions.
+     */
+    toOrderedMap(): OrderedMap<K, V>;
+
+    /**
+     * Converts this Collection to a Set, discarding keys. Throws if values
+     * are not hashable.
+     *
+     * Note: This is equivalent to `Set(this)`, but provided to allow for
+     * chained expressions.
+     */
+    toSet(): Set<V>;
+
+    /**
+     * Converts this Collection to a Set, maintaining the order of iteration and
+     * discarding keys.
+     *
+     * Note: This is equivalent to `OrderedSet(this.valueSeq())`, but provided
+     * for convenience and to allow for chained expressions.
+     */
+    toOrderedSet(): OrderedSet<V>;
+
+    /**
+     * Converts this Collection to a List, discarding keys.
+     *
+     * This is similar to `List(collection)`, but provided to allow for chained
+     * expressions. However, when called on `Map` or other keyed collections,
+     * `collection.toList()` discards the keys and creates a list of only the
+     * values, whereas `List(collection)` creates a list of entry tuples.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map, List } = require('immutable')
+     * var myMap = Map({ a: 'Apple', b: 'Banana' })
+     * List(myMap) // List [ [ "a", "Apple" ], [ "b", "Banana" ] ]
+     * myMap.toList() // List [ "Apple", "Banana" ]
+     * ```
+     */
+    toList(): List<V>;
+
+    /**
+     * Converts this Collection to a Stack, discarding keys. Throws if values
+     * are not hashable.
+     *
+     * Note: This is equivalent to `Stack(this)`, but provided to allow for
+     * chained expressions.
+     */
+    toStack(): Stack<V>;
+
+    // Conversion to Seq
+
+    /**
+     * Converts this Collection to a Seq of the same kind (indexed,
+     * keyed, or set).
+     */
+    toSeq(): Seq<K, V>;
+
+    /**
+     * Returns a Seq.Keyed from this Collection where indices are treated as keys.
+     *
+     * This is useful if you want to operate on an
+     * Collection.Indexed and preserve the [index, value] pairs.
+     *
+     * The returned Seq will have identical iteration order as
+     * this Collection.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Seq } = require('immutable')
+     * const indexedSeq = Seq([ 'A', 'B', 'C' ])
+     * // Seq [ "A", "B", "C" ]
+     * indexedSeq.filter(v => v === 'B')
+     * // Seq [ "B" ]
+     * const keyedSeq = indexedSeq.toKeyedSeq()
+     * // Seq { 0: "A", 1: "B", 2: "C" }
+     * keyedSeq.filter(v => v === 'B')
+     * // Seq { 1: "B" }
+     * ```
+     */
+    toKeyedSeq(): Seq.Keyed<K, V>;
+
+    /**
+     * Returns an Seq.Indexed of the values of this Collection, discarding keys.
+     */
+    toIndexedSeq(): Seq.Indexed<V>;
+
+    /**
+     * Returns a Seq.Set of the values of this Collection, discarding keys.
+     */
+    toSetSeq(): Seq.Set<V>;
+
+    // Iterators
+
+    /**
+     * An iterator of this `Collection`'s keys.
+     *
+     * Note: this will return an ES6 iterator which does not support
+     * Immutable.js sequence algorithms. Use `keySeq` instead, if this is
+     * what you want.
+     */
+    keys(): IterableIterator<K>;
+
+    /**
+     * An iterator of this `Collection`'s values.
+     *
+     * Note: this will return an ES6 iterator which does not support
+     * Immutable.js sequence algorithms. Use `valueSeq` instead, if this is
+     * what you want.
+     */
+    values(): IterableIterator<V>;
+
+    /**
+     * An iterator of this `Collection`'s entries as `[ key, value ]` tuples.
+     *
+     * Note: this will return an ES6 iterator which does not support
+     * Immutable.js sequence algorithms. Use `entrySeq` instead, if this is
+     * what you want.
+     */
+    entries(): IterableIterator<[K, V]>;
+
+    [Symbol.iterator](): IterableIterator<unknown>;
+
+    // Collections (Seq)
+
+    /**
+     * Returns a new Seq.Indexed of the keys of this Collection,
+     * discarding values.
+     */
+    keySeq(): Seq.Indexed<K>;
+
+    /**
+     * Returns an Seq.Indexed of the values of this Collection, discarding keys.
+     */
+    valueSeq(): Seq.Indexed<V>;
+
+    /**
+     * Returns a new Seq.Indexed of [key, value] tuples.
+     */
+    entrySeq(): Seq.Indexed<[K, V]>;
+
+    // Sequence algorithms
+
+    /**
+     * Returns a new Collection of the same type with values passed through a
+     * `mapper` function.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Collection } = require('immutable')
+     * Collection({ a: 1, b: 2 }).map(x => 10 * x)
+     * // Seq { "a": 10, "b": 20 }
+     * ```
+     *
+     * Note: `map()` always returns a new instance, even if it produced the same
+     * value at every step.
+     */
+    map<M>(
+      mapper: (value: V, key: K, iter: this) => M,
+      context?: unknown
+    ): Collection<K, M>;
+
+    /**
+     * Note: used only for sets, which return Collection<M, M> but are otherwise
+     * identical to normal `map()`.
+     *
+     * @ignore
+     */
+    map(...args: Array<never>): unknown;
+
+    /**
+     * Returns a new Collection of the same type with only the entries for which
+     * the `predicate` function returns true.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map } = require('immutable')
+     * Map({ a: 1, b: 2, c: 3, d: 4}).filter(x => x % 2 === 0)
+     * // Map { "b": 2, "d": 4 }
+     * ```
+     *
+     * Note: `filter()` always returns a new instance, even if it results in
+     * not filtering out any values.
+     */
+    filter<F extends V>(
+      predicate: (value: V, key: K, iter: this) => value is F,
+      context?: unknown
+    ): Collection<K, F>;
+    filter(
+      predicate: (value: V, key: K, iter: this) => unknown,
+      context?: unknown
+    ): this;
+
+    /**
+     * Returns a new Collection of the same type with only the entries for which
+     * the `predicate` function returns false.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map } = require('immutable')
+     * Map({ a: 1, b: 2, c: 3, d: 4}).filterNot(x => x % 2 === 0)
+     * // Map { "a": 1, "c": 3 }
+     * ```
+     *
+     * Note: `filterNot()` always returns a new instance, even if it results in
+     * not filtering out any values.
+     */
+    filterNot(
+      predicate: (value: V, key: K, iter: this) => boolean,
+      context?: unknown
+    ): this;
+
+    /**
+     * Returns a new Collection with the values for which the `predicate`
+     * function returns false and another for which is returns true.
+     */
+    partition<F extends V, C>(
+      predicate: (this: C, value: V, key: K, iter: this) => value is F,
+      context?: C
+    ): [Collection<K, V>, Collection<K, F>];
+    partition<C>(
+      predicate: (this: C, value: V, key: K, iter: this) => unknown,
+      context?: C
+    ): [this, this];
+
+    /**
+     * Returns a new Collection of the same type in reverse order.
+     */
+    reverse(): this;
+
+    /**
+     * Returns a new Collection of the same type which includes the same entries,
+     * stably sorted by using a `comparator`.
+     *
+     * If a `comparator` is not provided, a default comparator uses `<` and `>`.
+     *
+     * `comparator(valueA, valueB)`:
+     *
+     *   * Returns `0` if the elements should not be swapped.
+     *   * Returns `-1` (or any negative number) if `valueA` comes before `valueB`
+     *   * Returns `1` (or any positive number) if `valueA` comes after `valueB`
+     *   * Alternatively, can return a value of the `PairSorting` enum type
+     *   * Is pure, i.e. it must always return the same value for the same pair
+     *     of values.
+     *
+     * When sorting collections which have no defined order, their ordered
+     * equivalents will be returned. e.g. `map.sort()` returns OrderedMap.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map } = require('immutable')
+     * Map({ "c": 3, "a": 1, "b": 2 }).sort((a, b) => {
+     *   if (a < b) { return -1; }
+     *   if (a > b) { return 1; }
+     *   if (a === b) { return 0; }
+     * });
+     * // OrderedMap { "a": 1, "b": 2, "c": 3 }
+     * ```
+     *
+     * Note: `sort()` Always returns a new instance, even if the original was
+     * already sorted.
+     *
+     * Note: This is always an eager operation.
+     */
+    sort(comparator?: Comparator<V>): this;
+
+    /**
+     * Like `sort`, but also accepts a `comparatorValueMapper` which allows for
+     * sorting by more sophisticated means:
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { Map } = require('immutable')
+     * const beattles = Map({
+     *   John: { name: "Lennon" },
+     *   Paul: { name: "McCartney" },
+     *   George: { name: "Harrison" },
+     *   Ringo: { name: "Starr" },
+     * });
+     * beattles.sortBy(member => member.name);
+     * ```
+     *
+     * Note: `sortBy()` Always returns a new instance, even if the original was
+     * already sorted.
+     *
+     * Note: This is always an eager operation.
+     */
+    sortBy<C>(
+      comparatorValueMapper: (value: V, key: K, iter: this) => C,
+      comparator?: Comparator<C>
+    ): this;
+
+    /**
+     * Returns a `Map` of `Collection`, grouped by the return
+     * value of the `grouper` function.
+     *
+     * Note: This is always an eager operation.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { List, Map } = require('immutable')
+     * const listOfMaps = List([
+     *   Map({ v: 0 }),
+     *   Map({ v: 1 }),
+     *   Map({ v: 1 }),
+     *   Map({ v: 0 }),
+     *   Map({ v: 2 })
+     * ])
+     * const groupsOfMaps = listOfMaps.groupBy(x => x.get('v'))
+     * // Map {
+     * //   0: List [ Map{ "v": 0 }, Map { "v": 0 } ],
+     * //   1: List [ Map{ "v": 1 }, Map { "v": 1 } ],
+     * //   2: List [ Map{ "v": 2 } ],
+     * // }
+     * ```
+     */
+    groupBy<G>(
+      grouper: (value: V, key: K, iter: this) => G,
+      context?: unknown
+    ): Map<G, this>;
+
+    // Side effects
+
+    /**
+     * The `sideEffect` is executed for every entry in the Collection.
+     *
+     * Unlike `Array#forEach`, if any call of `sideEffect` returns
+     * `false`, the iteration will stop. Returns the number of entries iterated
+     * (including the last iteration which returned false).
+     */
+    forEach(
+      sideEffect: (value: V, key: K, iter: this) => unknown,
+      context?: unknown
+    ): number;
+
+    // Creating subsets
+
+    /**
+     * Returns a new Collection of the same type representing a portion of this
+     * Collection from start up to but not including end.
+     *
+     * If begin is negative, it is offset from the end of the Collection. e.g.
+     * `slice(-2)` returns a Collection of the last two entries. If it is not
+     * provided the new Collection will begin at the beginning of this Collection.
+     *
+     * If end is negative, it is offset from the end of the Collection. e.g.
+     * `slice(0, -1)` returns a Collection of everything but the last entry. If
+     * it is not provided, the new Collection will continue through the end of
+     * this Collection.
+     *
+     * If the requested slice is equivalent to the current Collection, then it
+     * will return itself.
+     */
+    slice(begin?: number, end?: number): this;
+
+    /**
+     * Returns a new Collection of the same type containing all entries except
+     * the first.
+     */
+    rest(): this;
+
+    /**
+     * Returns a new Collection of the same type containing all entries except
+     * the last.
+     */
+    butLast(): this;
+
+    /**
+     * Returns a new Collection of the same type which excludes the first `amount`
+     * entries from this Collection.
+     */
+    skip(amount: number): this;
+
+    /**
+     * Returns a new Collection of the same type which excludes the last `amount`
+     * entries from this Collection.
+     */
+    skipLast(amount: number): this;
+
+    /**
+     * Returns a new Collection of the same type which includes entries starting
+     * from when `predicate` first returns false.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { List } = require('immutable')
+     * List([ 'dog', 'frog', 'cat', 'hat', 'god' ])
+     *   .skipWhile(x => x.match(/g/))
+     * // List [ "cat", "hat", "god" ]
+     * ```
+     */
+    skipWhile(
+      predicate: (value: V, key: K, iter: this) => boolean,
+      context?: unknown
+    ): this;
+
+    /**
+     * Returns a new Collection of the same type which includes entries starting
+     * from when `predicate` first returns true.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { List } = require('immutable')
+     * List([ 'dog', 'frog', 'cat', 'hat', 'god' ])
+     *   .skipUntil(x => x.match(/hat/))
+     * // List [ "hat", "god" ]
+     * ```
+     */
+    skipUntil(
+      predicate: (value: V, key: K, iter: this) => boolean,
+      context?: unknown
+    ): this;
+
+    /**
+     * Returns a new Collection of the same type which includes the first `amount`
+     * entries from this Collection.
+     */
+    take(amount: number): this;
+
+    /**
+     * Returns a new Collection of the same type which includes the last `amount`
+     * entries from this Collection.
+     */
+    takeLast(amount: number): this;
+
+    /**
+     * Returns a new Collection of the same type which includes entries from this
+     * Collection as long as the `predicate` returns true.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { List } = require('immutable')
+     * List([ 'dog', 'frog', 'cat', 'hat', 'god' ])
+     *   .takeWhile(x => x.match(/o/))
+     * // List [ "dog", "frog" ]
+     * ```
+     */
+    takeWhile(
+      predicate: (value: V, key: K, iter: this) => boolean,
+      context?: unknown
+    ): this;
+
+    /**
+     * Returns a new Collection of the same type which includes entries from this
+     * Collection as long as the `predicate` returns false.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { List } = require('immutable')
+     * List([ 'dog', 'frog', 'cat', 'hat', 'god' ])
+     *   .takeUntil(x => x.match(/at/))
+     * // List [ "dog", "frog" ]
+     * ```
+     */
+    takeUntil(
+      predicate: (value: V, key: K, iter: this) => boolean,
+      context?: unknown
+    ): this;
+
+    // Combination
+
+    /**
+     * Returns a new Collection of the same type with other values and
+     * collection-like concatenated to this one.
+     *
+     * For Seqs, all entries will be present in the resulting Seq, even if they
+     * have the same key.
+     */
+    concat(
+      ...valuesOrCollections: Array<unknown>
+    ): Collection<unknown, unknown>;
+
+    /**
+     * Flattens nested Collections.
+     *
+     * Will deeply flatten the Collection by default, returning a Collection of the
+     * same type, but a `depth` can be provided in the form of a number or
+     * boolean (where true means to shallowly flatten one level). A depth of 0
+     * (or shallow: false) will deeply flatten.
+     *
+     * Flattens only others Collection, not Arrays or Objects.
+     *
+     * Note: `flatten(true)` operates on Collection<unknown, Collection<K, V>> and
+     * returns Collection<K, V>
+     */
+    flatten(depth?: number): Collection<unknown, unknown>;
+    flatten(shallow?: boolean): Collection<unknown, unknown>;
+
+    /**
+     * Flat-maps the Collection, returning a Collection of the same type.
+     *
+     * Similar to `collection.map(...).flatten(true)`.
+     */
+    flatMap<M>(
+      mapper: (value: V, key: K, iter: this) => Iterable<M>,
+      context?: unknown
+    ): Collection<K, M>;
+
+    /**
+     * Flat-maps the Collection, returning a Collection of the same type.
+     *
+     * Similar to `collection.map(...).flatten(true)`.
+     * Used for Dictionaries only.
+     */
+    flatMap<KM, VM>(
+      mapper: (value: V, key: K, iter: this) => Iterable<[KM, VM]>,
+      context?: unknown
+    ): Collection<KM, VM>;
+
+    // Reducing a value
+
+    /**
+     * Reduces the Collection to a value by calling the `reducer` for every entry
+     * in the Collection and passing along the reduced value.
+     *
+     * If `initialReduction` is not provided, the first item in the
+     * Collection will be used.
+     *
+     * @see `Array#reduce`.
+     */
+    reduce<R>(
+      reducer: (reduction: R, value: V, key: K, iter: this) => R,
+      initialReduction: R,
+      context?: unknown
+    ): R;
+    reduce<R>(
+      reducer: (reduction: V | R, value: V, key: K, iter: this) => R
+    ): R;
+
+    /**
+     * Reduces the Collection in reverse (from the right side).
+     *
+     * Note: Similar to this.reverse().reduce(), and provided for parity
+     * with `Array#reduceRight`.
+     */
+    reduceRight<R>(
+      reducer: (reduction: R, value: V, key: K, iter: this) => R,
+      initialReduction: R,
+      context?: unknown
+    ): R;
+    reduceRight<R>(
+      reducer: (reduction: V | R, value: V, key: K, iter: this) => R
+    ): R;
+
+    /**
+     * True if `predicate` returns true for all entries in the Collection.
+     */
+    every(
+      predicate: (value: V, key: K, iter: this) => boolean,
+      context?: unknown
+    ): boolean;
+
+    /**
+     * True if `predicate` returns true for any entry in the Collection.
+     */
+    some(
+      predicate: (value: V, key: K, iter: this) => boolean,
+      context?: unknown
+    ): boolean;
+
+    /**
+     * Joins values together as a string, inserting a separator between each.
+     * The default separator is `","`.
+     */
+    join(separator?: string): string;
+
+    /**
+     * Returns true if this Collection includes no values.
+     *
+     * For some lazy `Seq`, `isEmpty` might need to iterate to determine
+     * emptiness. At most one iteration will occur.
+     */
+    isEmpty(): boolean;
+
+    /**
+     * Returns the size of this Collection.
+     *
+     * Regardless of if this Collection can describe its size lazily (some Seqs
+     * cannot), this method will always return the correct size. E.g. it
+     * evaluates a lazy `Seq` if necessary.
+     *
+     * If `predicate` is provided, then this returns the count of entries in the
+     * Collection for which the `predicate` returns true.
+     */
+    count(): number;
+    count(
+      predicate: (value: V, key: K, iter: this) => boolean,
+      context?: unknown
+    ): number;
+
+    /**
+     * Returns a `Seq.Keyed` of counts, grouped by the return value of
+     * the `grouper` function.
+     *
+     * Note: This is not a lazy operation.
+     */
+    countBy<G>(
+      grouper: (value: V, key: K, iter: this) => G,
+      context?: unknown
+    ): Map<G, number>;
+
+    // Search for value
+
+    /**
+     * Returns the first value for which the `predicate` returns true.
+     */
+    find(
+      predicate: (value: V, key: K, iter: this) => boolean,
+      context?: unknown,
+      notSetValue?: V
+    ): V | undefined;
+
+    /**
+     * Returns the last value for which the `predicate` returns true.
+     *
+     * Note: `predicate` will be called for each entry in reverse.
+     */
+    findLast(
+      predicate: (value: V, key: K, iter: this) => boolean,
+      context?: unknown,
+      notSetValue?: V
+    ): V | undefined;
+
+    /**
+     * Returns the first [key, value] entry for which the `predicate` returns true.
+     */
+    findEntry(
+      predicate: (value: V, key: K, iter: this) => boolean,
+      context?: unknown,
+      notSetValue?: V
+    ): [K, V] | undefined;
+
+    /**
+     * Returns the last [key, value] entry for which the `predicate`
+     * returns true.
+     *
+     * Note: `predicate` will be called for each entry in reverse.
+     */
+    findLastEntry(
+      predicate: (value: V, key: K, iter: this) => boolean,
+      context?: unknown,
+      notSetValue?: V
+    ): [K, V] | undefined;
+
+    /**
+     * Returns the key for which the `predicate` returns true.
+     */
+    findKey(
+      predicate: (value: V, key: K, iter: this) => boolean,
+      context?: unknown
+    ): K | undefined;
+
+    /**
+     * Returns the last key for which the `predicate` returns true.
+     *
+     * Note: `predicate` will be called for each entry in reverse.
+     */
+    findLastKey(
+      predicate: (value: V, key: K, iter: this) => boolean,
+      context?: unknown
+    ): K | undefined;
+
+    /**
+     * Returns the key associated with the search value, or undefined.
+     */
+    keyOf(searchValue: V): K | undefined;
+
+    /**
+     * Returns the last key associated with the search value, or undefined.
+     */
+    lastKeyOf(searchValue: V): K | undefined;
+
+    /**
+     * Returns the maximum value in this collection. If any values are
+     * comparatively equivalent, the first one found will be returned.
+     *
+     * The `comparator` is used in the same way as `Collection#sort`. If it is not
+     * provided, the default comparator is `>`.
+     *
+     * When two values are considered equivalent, the first encountered will be
+     * returned. Otherwise, `max` will operate independent of the order of input
+     * as long as the comparator is commutative. The default comparator `>` is
+     * commutative *only* when types do not differ.
+     *
+     * If `comparator` returns 0 and either value is NaN, undefined, or null,
+     * that value will be returned.
+     */
+    max(comparator?: Comparator<V>): V | undefined;
+
+    /**
+     * Like `max`, but also accepts a `comparatorValueMapper` which allows for
+     * comparing by more sophisticated means:
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { List, } = require('immutable');
+     * const l = List([
+     *   { name: 'Bob', avgHit: 1 },
+     *   { name: 'Max', avgHit: 3 },
+     *   { name: 'Lili', avgHit: 2 } ,
+     * ]);
+     * l.maxBy(i => i.avgHit); // will output { name: 'Max', avgHit: 3 }
+     * ```
+     */
+    maxBy<C>(
+      comparatorValueMapper: (value: V, key: K, iter: this) => C,
+      comparator?: Comparator<C>
+    ): V | undefined;
+
+    /**
+     * Returns the minimum value in this collection. If any values are
+     * comparatively equivalent, the first one found will be returned.
+     *
+     * The `comparator` is used in the same way as `Collection#sort`. If it is not
+     * provided, the default comparator is `<`.
+     *
+     * When two values are considered equivalent, the first encountered will be
+     * returned. Otherwise, `min` will operate independent of the order of input
+     * as long as the comparator is commutative. The default comparator `<` is
+     * commutative *only* when types do not differ.
+     *
+     * If `comparator` returns 0 and either value is NaN, undefined, or null,
+     * that value will be returned.
+     */
+    min(comparator?: Comparator<V>): V | undefined;
+
+    /**
+     * Like `min`, but also accepts a `comparatorValueMapper` which allows for
+     * comparing by more sophisticated means:
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { List, } = require('immutable');
+     * const l = List([
+     *   { name: 'Bob', avgHit: 1 },
+     *   { name: 'Max', avgHit: 3 },
+     *   { name: 'Lili', avgHit: 2 } ,
+     * ]);
+     * l.minBy(i => i.avgHit); // will output { name: 'Bob', avgHit: 1 }
+     * ```
+     */
+    minBy<C>(
+      comparatorValueMapper: (value: V, key: K, iter: this) => C,
+      comparator?: Comparator<C>
+    ): V | undefined;
+
+    // Comparison
+
+    /**
+     * True if `iter` includes every value in this Collection.
+     */
+    isSubset(iter: Iterable<V>): boolean;
+
+    /**
+     * True if this Collection includes every value in `iter`.
+     */
+    isSuperset(iter: Iterable<V>): boolean;
+  }
+
+  /**
+   * The interface to fulfill to qualify as a Value Object.
+   */
+  interface ValueObject {
+    /**
+     * True if this and the other Collection have value equality, as defined
+     * by `Immutable.is()`.
+     *
+     * Note: This is equivalent to `Immutable.is(this, other)`, but provided to
+     * allow for chained expressions.
+     */
+    equals(other: unknown): boolean;
+
+    /**
+     * Computes and returns the hashed identity for this Collection.
+     *
+     * The `hashCode` of a Collection is used to determine potential equality,
+     * and is used when adding this to a `Set` or as a key in a `Map`, enabling
+     * lookup via a different instance.
+     *
+     * <!-- runkit:activate -->
+     * ```js
+     * const { List, Set } = require('immutable');
+     * const a = List([ 1, 2, 3 ]);
+     * const b = List([ 1, 2, 3 ]);
+     * assert.notStrictEqual(a, b); // different instances
+     * const set = Set([ a ]);
+     * assert.equal(set.has(b), true);
+     * ```
+     *
+     * Note: hashCode() MUST return a Uint32 number. The easiest way to
+     * guarantee this is to return `myHash | 0` from a custom implementation.
+     *
+     * If two values have the same `hashCode`, they are [not guaranteed
+     * to be equal][Hash Collision]. If two values have different `hashCode`s,
+     * they must not be equal.
+     *
+     * Note: `hashCode()` is not guaranteed to always be called before
+     * `equals()`. Most but not all Immutable.js collections use hash codes to
+     * organize their internal data structures, while all Immutable.js
+     * collections use equality during lookups.
+     *
+     * [Hash Collision]: https://en.wikipedia.org/wiki/Collision_(computer_science)
+     */
+    hashCode(): number;
+  }
+
+  /**
+   * Deeply converts plain JS objects and arrays to Immutable Maps and Lists.
+   *
+   * `fromJS` will convert Arrays and [array-like objects][2] to a List, and
+   * plain objects (without a custom prototype) to a Map. [Iterable objects][3]
+   * may be converted to List, Map, or Set.
+   *
+   * If a `reviver` is optionally provided, it will be called with every
+   * collection as a Seq (beginning with the most nested collections
+   * and proceeding to the top-level collection itself), along with the key
+   * referring to each collection and the parent JS object provided as `this`.
+   * For the top level, object, the key will be `""`. This `reviver` is expected
+   * to return a new Immutable Collection, allowing for custom conversions from
+   * deep JS objects. Finally, a `path` is provided which is the sequence of
+   * keys to this value from the starting value.
+   *
+   * `reviver` acts similarly to the [same parameter in `JSON.parse`][1].
+   *
+   * If `reviver` is not provided, the default behavior will convert Objects
+   * into Maps and Arrays into Lists like so:
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { fromJS, isKeyed } = require('immutable')
+   * function (key, value) {
+   *   return isKeyed(value) ? value.toMap() : value.toList()
+   * }
+   * ```
+   *
+   * Accordingly, this example converts native JS data to OrderedMap and List:
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { fromJS, isKeyed } = require('immutable')
+   * fromJS({ a: {b: [10, 20, 30]}, c: 40}, function (key, value, path) {
+   *   console.log(key, value, path)
+   *   return isKeyed(value) ? value.toOrderedMap() : value.toList()
+   * })
+   *
+   * > "b", [ 10, 20, 30 ], [ "a", "b" ]
+   * > "a", {b: [10, 20, 30]}, [ "a" ]
+   * > "", {a: {b: [10, 20, 30]}, c: 40}, []
+   * ```
+   *
+   * Keep in mind, when using JS objects to construct Immutable Maps, that
+   * JavaScript Object properties are always strings, even if written in a
+   * quote-less shorthand, while Immutable Maps accept keys of any type.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { Map } = require('immutable')
+   * let obj = { 1: "one" };
+   * Object.keys(obj); // [ "1" ]
+   * assert.equal(obj["1"], obj[1]); // "one" === "one"
+   *
+   * let map = Map(obj);
+   * assert.notEqual(map.get("1"), map.get(1)); // "one" !== undefined
+   * ```
+   *
+   * Property access for JavaScript Objects first converts the key to a string,
+   * but since Immutable Map keys can be of any type the argument to `get()` is
+   * not altered.
+   *
+   * [1]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse#Example.3A_Using_the_reviver_parameter
+   *      "Using the reviver parameter"
+   * [2]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Indexed_collections#working_with_array-like_objects
+   *      "Working with array-like objects"
+   * [3]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#the_iterable_protocol
+   *      "The iterable protocol"
+   */
+  function fromJS<JSValue>(
+    jsValue: JSValue,
+    reviver?: undefined
+  ): FromJS<JSValue>;
+  function fromJS(
+    jsValue: unknown,
+    reviver?: (
+      key: string | number,
+      sequence: Collection.Keyed<string, unknown> | Collection.Indexed<unknown>,
+      path?: Array<string | number>
+    ) => unknown
+  ): Collection<unknown, unknown>;
+
+  type FromJS<JSValue> = JSValue extends FromJSNoTransform
+    ? JSValue
+    : JSValue extends Array<any>
+    ? FromJSArray<JSValue>
+    : JSValue extends {}
+    ? FromJSObject<JSValue>
+    : any;
+
+  type FromJSNoTransform =
+    | Collection<any, any>
+    | number
+    | string
+    | null
+    | undefined;
+
+  type FromJSArray<JSValue> = JSValue extends Array<infer T>
+    ? List<FromJS<T>>
+    : never;
+
+  type FromJSObject<JSValue> = JSValue extends {}
+    ? Map<keyof JSValue, FromJS<JSValue[keyof JSValue]>>
+    : never;
+
+  /**
+   * Value equality check with semantics similar to `Object.is`, but treats
+   * Immutable `Collection`s as values, equal if the second `Collection` includes
+   * equivalent values.
+   *
+   * It's used throughout Immutable when checking for equality, including `Map`
+   * key equality and `Set` membership.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { Map, is } = require('immutable')
+   * const map1 = Map({ a: 1, b: 1, c: 1 })
+   * const map2 = Map({ a: 1, b: 1, c: 1 })
+   * assert.equal(map1 !== map2, true)
+   * assert.equal(Object.is(map1, map2), false)
+   * assert.equal(is(map1, map2), true)
+   * ```
+   *
+   * `is()` compares primitive types like strings and numbers, Immutable.js
+   * collections like `Map` and `List`, but also any custom object which
+   * implements `ValueObject` by providing `equals()` and `hashCode()` methods.
+   *
+   * Note: Unlike `Object.is`, `Immutable.is` assumes `0` and `-0` are the same
+   * value, matching the behavior of ES6 Map key equality.
+   */
+  function is(first: unknown, second: unknown): boolean;
+
+  /**
+   * The `hash()` function is an important part of how Immutable determines if
+   * two values are equivalent and is used to determine how to store those
+   * values. Provided with any value, `hash()` will return a 31-bit integer.
+   *
+   * When designing Objects which may be equal, it's important that when a
+   * `.equals()` method returns true, that both values `.hashCode()` method
+   * return the same value. `hash()` may be used to produce those values.
+   *
+   * For non-Immutable Objects that do not provide a `.hashCode()` functions
+   * (including plain Objects, plain Arrays, Date objects, etc), a unique hash
+   * value will be created for each *instance*. That is, the create hash
+   * represents referential equality, and not value equality for Objects. This
+   * ensures that if that Object is mutated over time that its hash code will
+   * remain consistent, allowing Objects to be used as keys and values in
+   * Immutable.js collections.
+   *
+   * Note that `hash()` attempts to balance between speed and avoiding
+   * collisions, however it makes no attempt to produce secure hashes.
+   *
+   * *New in Version 4.0*
+   */
+  function hash(value: unknown): number;
+
+  /**
+   * True if `maybeImmutable` is an Immutable Collection or Record.
+   *
+   * Note: Still returns true even if the collections is within a `withMutations()`.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { isImmutable, Map, List, Stack } = require('immutable');
+   * isImmutable([]); // false
+   * isImmutable({}); // false
+   * isImmutable(Map()); // true
+   * isImmutable(List()); // true
+   * isImmutable(Stack()); // true
+   * isImmutable(Map().asMutable()); // true
+   * ```
+   */
+  function isImmutable(
+    maybeImmutable: unknown
+  ): maybeImmutable is Collection<unknown, unknown>;
+
+  /**
+   * True if `maybeCollection` is a Collection, or any of its subclasses.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { isCollection, Map, List, Stack } = require('immutable');
+   * isCollection([]); // false
+   * isCollection({}); // false
+   * isCollection(Map()); // true
+   * isCollection(List()); // true
+   * isCollection(Stack()); // true
+   * ```
+   */
+  function isCollection(
+    maybeCollection: unknown
+  ): maybeCollection is Collection<unknown, unknown>;
+
+  /**
+   * True if `maybeKeyed` is a Collection.Keyed, or any of its subclasses.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { isKeyed, Map, List, Stack } = require('immutable');
+   * isKeyed([]); // false
+   * isKeyed({}); // false
+   * isKeyed(Map()); // true
+   * isKeyed(List()); // false
+   * isKeyed(Stack()); // false
+   * ```
+   */
+  function isKeyed(
+    maybeKeyed: unknown
+  ): maybeKeyed is Collection.Keyed<unknown, unknown>;
+
+  /**
+   * True if `maybeIndexed` is a Collection.Indexed, or any of its subclasses.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { isIndexed, Map, List, Stack, Set } = require('immutable');
+   * isIndexed([]); // false
+   * isIndexed({}); // false
+   * isIndexed(Map()); // false
+   * isIndexed(List()); // true
+   * isIndexed(Stack()); // true
+   * isIndexed(Set()); // false
+   * ```
+   */
+  function isIndexed(
+    maybeIndexed: unknown
+  ): maybeIndexed is Collection.Indexed<unknown>;
+
+  /**
+   * True if `maybeAssociative` is either a Keyed or Indexed Collection.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { isAssociative, Map, List, Stack, Set } = require('immutable');
+   * isAssociative([]); // false
+   * isAssociative({}); // false
+   * isAssociative(Map()); // true
+   * isAssociative(List()); // true
+   * isAssociative(Stack()); // true
+   * isAssociative(Set()); // false
+   * ```
+   */
+  function isAssociative(
+    maybeAssociative: unknown
+  ): maybeAssociative is
+    | Collection.Keyed<unknown, unknown>
+    | Collection.Indexed<unknown>;
+
+  /**
+   * True if `maybeOrdered` is a Collection where iteration order is well
+   * defined. True for Collection.Indexed as well as OrderedMap and OrderedSet.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { isOrdered, Map, OrderedMap, List, Set } = require('immutable');
+   * isOrdered([]); // false
+   * isOrdered({}); // false
+   * isOrdered(Map()); // false
+   * isOrdered(OrderedMap()); // true
+   * isOrdered(List()); // true
+   * isOrdered(Set()); // false
+   * ```
+   */
+  function isOrdered(maybeOrdered: unknown): boolean;
+
+  /**
+   * True if `maybeValue` is a JavaScript Object which has *both* `equals()`
+   * and `hashCode()` methods.
+   *
+   * Any two instances of *value objects* can be compared for value equality with
+   * `Immutable.is()` and can be used as keys in a `Map` or members in a `Set`.
+   */
+  function isValueObject(maybeValue: unknown): maybeValue is ValueObject;
+
+  /**
+   * True if `maybeSeq` is a Seq.
+   */
+  function isSeq(
+    maybeSeq: unknown
+  ): maybeSeq is
+    | Seq.Indexed<unknown>
+    | Seq.Keyed<unknown, unknown>
+    | Seq.Set<unknown>;
+
+  /**
+   * True if `maybeList` is a List.
+   */
+  function isList(maybeList: unknown): maybeList is List<unknown>;
+
+  /**
+   * True if `maybeMap` is a Map.
+   *
+   * Also true for OrderedMaps.
+   */
+  function isMap(maybeMap: unknown): maybeMap is Map<unknown, unknown>;
+
+  /**
+   * True if `maybeOrderedMap` is an OrderedMap.
+   */
+  function isOrderedMap(
+    maybeOrderedMap: unknown
+  ): maybeOrderedMap is OrderedMap<unknown, unknown>;
+
+  /**
+   * True if `maybeStack` is a Stack.
+   */
+  function isStack(maybeStack: unknown): maybeStack is Stack<unknown>;
+
+  /**
+   * True if `maybeSet` is a Set.
+   *
+   * Also true for OrderedSets.
+   */
+  function isSet(maybeSet: unknown): maybeSet is Set<unknown>;
+
+  /**
+   * True if `maybeOrderedSet` is an OrderedSet.
+   */
+  function isOrderedSet(
+    maybeOrderedSet: unknown
+  ): maybeOrderedSet is OrderedSet<unknown>;
+
+  /**
+   * True if `maybeRecord` is a Record.
+   */
+  function isRecord(maybeRecord: unknown): maybeRecord is Record<{}>;
+
+  /**
+   * Returns the value within the provided collection associated with the
+   * provided key, or notSetValue if the key is not defined in the collection.
+   *
+   * A functional alternative to `collection.get(key)` which will also work on
+   * plain Objects and Arrays as an alternative for `collection[key]`.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { get } = require('immutable')
+   * get([ 'dog', 'frog', 'cat' ], 2) // 'frog'
+   * get({ x: 123, y: 456 }, 'x') // 123
+   * get({ x: 123, y: 456 }, 'z', 'ifNotSet') // 'ifNotSet'
+   * ```
+   */
+  function get<K, V>(collection: Collection<K, V>, key: K): V | undefined;
+  function get<K, V, NSV>(
+    collection: Collection<K, V>,
+    key: K,
+    notSetValue: NSV
+  ): V | NSV;
+  function get<TProps extends object, K extends keyof TProps>(
+    record: Record<TProps>,
+    key: K,
+    notSetValue: unknown
+  ): TProps[K];
+  function get<V>(collection: Array<V>, key: number): V | undefined;
+  function get<V, NSV>(
+    collection: Array<V>,
+    key: number,
+    notSetValue: NSV
+  ): V | NSV;
+  function get<C extends object, K extends keyof C>(
+    object: C,
+    key: K,
+    notSetValue: unknown
+  ): C[K];
+  function get<V>(collection: { [key: string]: V }, key: string): V | undefined;
+  function get<V, NSV>(
+    collection: { [key: string]: V },
+    key: string,
+    notSetValue: NSV
+  ): V | NSV;
+
+  /**
+   * Returns true if the key is defined in the provided collection.
+   *
+   * A functional alternative to `collection.has(key)` which will also work with
+   * plain Objects and Arrays as an alternative for
+   * `collection.hasOwnProperty(key)`.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { has } = require('immutable')
+   * has([ 'dog', 'frog', 'cat' ], 2) // true
+   * has([ 'dog', 'frog', 'cat' ], 5) // false
+   * has({ x: 123, y: 456 }, 'x') // true
+   * has({ x: 123, y: 456 }, 'z') // false
+   * ```
+   */
+  function has(collection: object, key: unknown): boolean;
+
+  /**
+   * Returns a copy of the collection with the value at key removed.
+   *
+   * A functional alternative to `collection.remove(key)` which will also work
+   * with plain Objects and Arrays as an alternative for
+   * `delete collectionCopy[key]`.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { remove } = require('immutable')
+   * const originalArray = [ 'dog', 'frog', 'cat' ]
+   * remove(originalArray, 1) // [ 'dog', 'cat' ]
+   * console.log(originalArray) // [ 'dog', 'frog', 'cat' ]
+   * const originalObject = { x: 123, y: 456 }
+   * remove(originalObject, 'x') // { y: 456 }
+   * console.log(originalObject) // { x: 123, y: 456 }
+   * ```
+   */
+  function remove<K, C extends Collection<K, unknown>>(
+    collection: C,
+    key: K
+  ): C;
+  function remove<
+    TProps extends object,
+    C extends Record<TProps>,
+    K extends keyof TProps
+  >(collection: C, key: K): C;
+  function remove<C extends Array<unknown>>(collection: C, key: number): C;
+  function remove<C, K extends keyof C>(collection: C, key: K): C;
+  function remove<C extends { [key: string]: unknown }, K extends keyof C>(
+    collection: C,
+    key: K
+  ): C;
+
+  /**
+   * Returns a copy of the collection with the value at key set to the provided
+   * value.
+   *
+   * A functional alternative to `collection.set(key, value)` which will also
+   * work with plain Objects and Arrays as an alternative for
+   * `collectionCopy[key] = value`.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { set } = require('immutable')
+   * const originalArray = [ 'dog', 'frog', 'cat' ]
+   * set(originalArray, 1, 'cow') // [ 'dog', 'cow', 'cat' ]
+   * console.log(originalArray) // [ 'dog', 'frog', 'cat' ]
+   * const originalObject = { x: 123, y: 456 }
+   * set(originalObject, 'x', 789) // { x: 789, y: 456 }
+   * console.log(originalObject) // { x: 123, y: 456 }
+   * ```
+   */
+  function set<K, V, C extends Collection<K, V>>(
+    collection: C,
+    key: K,
+    value: V
+  ): C;
+  function set<
+    TProps extends object,
+    C extends Record<TProps>,
+    K extends keyof TProps
+  >(record: C, key: K, value: TProps[K]): C;
+  function set<V, C extends Array<V>>(collection: C, key: number, value: V): C;
+  function set<C, K extends keyof C>(object: C, key: K, value: C[K]): C;
+  function set<V, C extends { [key: string]: V }>(
+    collection: C,
+    key: string,
+    value: V
+  ): C;
+
+  /**
+   * Returns a copy of the collection with the value at key set to the result of
+   * providing the existing value to the updating function.
+   *
+   * A functional alternative to `collection.update(key, fn)` which will also
+   * work with plain Objects and Arrays as an alternative for
+   * `collectionCopy[key] = fn(collection[key])`.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { update } = require('immutable')
+   * const originalArray = [ 'dog', 'frog', 'cat' ]
+   * update(originalArray, 1, val => val.toUpperCase()) // [ 'dog', 'FROG', 'cat' ]
+   * console.log(originalArray) // [ 'dog', 'frog', 'cat' ]
+   * const originalObject = { x: 123, y: 456 }
+   * update(originalObject, 'x', val => val * 6) // { x: 738, y: 456 }
+   * console.log(originalObject) // { x: 123, y: 456 }
+   * ```
+   */
+  function update<K, V, C extends Collection<K, V>>(
+    collection: C,
+    key: K,
+    updater: (value: V | undefined) => V | undefined
+  ): C;
+  function update<K, V, C extends Collection<K, V>, NSV>(
+    collection: C,
+    key: K,
+    notSetValue: NSV,
+    updater: (value: V | NSV) => V
+  ): C;
+  function update<
+    TProps extends object,
+    C extends Record<TProps>,
+    K extends keyof TProps
+  >(record: C, key: K, updater: (value: TProps[K]) => TProps[K]): C;
+  function update<
+    TProps extends object,
+    C extends Record<TProps>,
+    K extends keyof TProps,
+    NSV
+  >(
+    record: C,
+    key: K,
+    notSetValue: NSV,
+    updater: (value: TProps[K] | NSV) => TProps[K]
+  ): C;
+  function update<V>(
+    collection: Array<V>,
+    key: number,
+    updater: (value: V | undefined) => V | undefined
+  ): Array<V>;
+  function update<V, NSV>(
+    collection: Array<V>,
+    key: number,
+    notSetValue: NSV,
+    updater: (value: V | NSV) => V
+  ): Array<V>;
+  function update<C, K extends keyof C>(
+    object: C,
+    key: K,
+    updater: (value: C[K]) => C[K]
+  ): C;
+  function update<C, K extends keyof C, NSV>(
+    object: C,
+    key: K,
+    notSetValue: NSV,
+    updater: (value: C[K] | NSV) => C[K]
+  ): C;
+  function update<V, C extends { [key: string]: V }, K extends keyof C>(
+    collection: C,
+    key: K,
+    updater: (value: V) => V
+  ): { [key: string]: V };
+  function update<V, C extends { [key: string]: V }, K extends keyof C, NSV>(
+    collection: C,
+    key: K,
+    notSetValue: NSV,
+    updater: (value: V | NSV) => V
+  ): { [key: string]: V };
+
+  /**
+   * Returns the value at the provided key path starting at the provided
+   * collection, or notSetValue if the key path is not defined.
+   *
+   * A functional alternative to `collection.getIn(keypath)` which will also
+   * work with plain Objects and Arrays.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { getIn } = require('immutable')
+   * getIn({ x: { y: { z: 123 }}}, ['x', 'y', 'z']) // 123
+   * getIn({ x: { y: { z: 123 }}}, ['x', 'q', 'p'], 'ifNotSet') // 'ifNotSet'
+   * ```
+   */
+  function getIn(
+    collection: unknown,
+    keyPath: Iterable<unknown>,
+    notSetValue?: unknown
+  ): unknown;
+
+  /**
+   * Returns true if the key path is defined in the provided collection.
+   *
+   * A functional alternative to `collection.hasIn(keypath)` which will also
+   * work with plain Objects and Arrays.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { hasIn } = require('immutable')
+   * hasIn({ x: { y: { z: 123 }}}, ['x', 'y', 'z']) // true
+   * hasIn({ x: { y: { z: 123 }}}, ['x', 'q', 'p']) // false
+   * ```
+   */
+  function hasIn(collection: unknown, keyPath: Iterable<unknown>): boolean;
+
+  /**
+   * Returns a copy of the collection with the value at the key path removed.
+   *
+   * A functional alternative to `collection.removeIn(keypath)` which will also
+   * work with plain Objects and Arrays.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { removeIn } = require('immutable')
+   * const original = { x: { y: { z: 123 }}}
+   * removeIn(original, ['x', 'y', 'z']) // { x: { y: {}}}
+   * console.log(original) // { x: { y: { z: 123 }}}
+   * ```
+   */
+  function removeIn<C>(collection: C, keyPath: Iterable<unknown>): C;
+
+  /**
+   * Returns a copy of the collection with the value at the key path set to the
+   * provided value.
+   *
+   * A functional alternative to `collection.setIn(keypath)` which will also
+   * work with plain Objects and Arrays.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { setIn } = require('immutable')
+   * const original = { x: { y: { z: 123 }}}
+   * setIn(original, ['x', 'y', 'z'], 456) // { x: { y: { z: 456 }}}
+   * console.log(original) // { x: { y: { z: 123 }}}
+   * ```
+   */
+  function setIn<C>(
+    collection: C,
+    keyPath: Iterable<unknown>,
+    value: unknown
+  ): C;
+
+  /**
+   * Returns a copy of the collection with the value at key path set to the
+   * result of providing the existing value to the updating function.
+   *
+   * A functional alternative to `collection.updateIn(keypath)` which will also
+   * work with plain Objects and Arrays.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { updateIn } = require('immutable')
+   * const original = { x: { y: { z: 123 }}}
+   * updateIn(original, ['x', 'y', 'z'], val => val * 6) // { x: { y: { z: 738 }}}
+   * console.log(original) // { x: { y: { z: 123 }}}
+   * ```
+   */
+  function updateIn<C>(
+    collection: C,
+    keyPath: Iterable<unknown>,
+    updater: (value: unknown) => unknown
+  ): C;
+  function updateIn<C>(
+    collection: C,
+    keyPath: Iterable<unknown>,
+    notSetValue: unknown,
+    updater: (value: unknown) => unknown
+  ): C;
+
+  /**
+   * Returns a copy of the collection with the remaining collections merged in.
+   *
+   * A functional alternative to `collection.merge()` which will also work with
+   * plain Objects and Arrays.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { merge } = require('immutable')
+   * const original = { x: 123, y: 456 }
+   * merge(original, { y: 789, z: 'abc' }) // { x: 123, y: 789, z: 'abc' }
+   * console.log(original) // { x: 123, y: 456 }
+   * ```
+   */
+  function merge<C>(
+    collection: C,
+    ...collections: Array<
+      | Iterable<unknown>
+      | Iterable<[unknown, unknown]>
+      | { [key: string]: unknown }
+    >
+  ): C;
+
+  /**
+   * Returns a copy of the collection with the remaining collections merged in,
+   * calling the `merger` function whenever an existing value is encountered.
+   *
+   * A functional alternative to `collection.mergeWith()` which will also work
+   * with plain Objects and Arrays.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { mergeWith } = require('immutable')
+   * const original = { x: 123, y: 456 }
+   * mergeWith(
+   *   (oldVal, newVal) => oldVal + newVal,
+   *   original,
+   *   { y: 789, z: 'abc' }
+   * ) // { x: 123, y: 1245, z: 'abc' }
+   * console.log(original) // { x: 123, y: 456 }
+   * ```
+   */
+  function mergeWith<C>(
+    merger: (oldVal: unknown, newVal: unknown, key: unknown) => unknown,
+    collection: C,
+    ...collections: Array<
+      | Iterable<unknown>
+      | Iterable<[unknown, unknown]>
+      | { [key: string]: unknown }
+    >
+  ): C;
+
+  /**
+   * Like `merge()`, but when two compatible collections are encountered with
+   * the same key, it merges them as well, recursing deeply through the nested
+   * data. Two collections are considered to be compatible (and thus will be
+   * merged together) if they both fall into one of three categories: keyed
+   * (e.g., `Map`s, `Record`s, and objects), indexed (e.g., `List`s and
+   * arrays), or set-like (e.g., `Set`s). If they fall into separate
+   * categories, `mergeDeep` will replace the existing collection with the
+   * collection being merged in. This behavior can be customized by using
+   * `mergeDeepWith()`.
+   *
+   * Note: Indexed and set-like collections are merged using
+   * `concat()`/`union()` and therefore do not recurse.
+   *
+   * A functional alternative to `collection.mergeDeep()` which will also work
+   * with plain Objects and Arrays.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { mergeDeep } = require('immutable')
+   * const original = { x: { y: 123 }}
+   * mergeDeep(original, { x: { z: 456 }}) // { x: { y: 123, z: 456 }}
+   * console.log(original) // { x: { y: 123 }}
+   * ```
+   */
+  function mergeDeep<C>(
+    collection: C,
+    ...collections: Array<
+      | Iterable<unknown>
+      | Iterable<[unknown, unknown]>
+      | { [key: string]: unknown }
+    >
+  ): C;
+
+  /**
+   * Like `mergeDeep()`, but when two non-collections or incompatible
+   * collections are encountered at the same key, it uses the `merger` function
+   * to determine the resulting value. Collections are considered incompatible
+   * if they fall into separate categories between keyed, indexed, and set-like.
+   *
+   * A functional alternative to `collection.mergeDeepWith()` which will also
+   * work with plain Objects and Arrays.
+   *
+   * <!-- runkit:activate -->
+   * ```js
+   * const { mergeDeepWith } = require('immutable')
+   * const original = { x: { y: 123 }}
+   * mergeDeepWith(
+   *   (oldVal, newVal) => oldVal + newVal,
+   *   original,
+   *   { x: { y: 456 }}
+   * ) // { x: { y: 579 }}
+   * console.log(original) // { x: { y: 123 }}
+   * ```
+   */
+  function mergeDeepWith<C>(
+    merger: (oldVal: unknown, newVal: unknown, key: unknown) => unknown,
+    collection: C,
+    ...collections: Array<
+      | Iterable<unknown>
+      | Iterable<[unknown, unknown]>
+      | { [key: string]: unknown }
+    >
+  ): C;
+}
+
+/**
+ * Defines the main export of the immutable module to be the Immutable namespace
+ * This supports many common module import patterns:
+ *
+ *     const Immutable = require("immutable");
+ *     const { List } = require("immutable");
+ *     import Immutable from "immutable";
+ *     import * as Immutable from "immutable";
+ *     import { List } from "immutable";
+ *
+ */
+export = Immutable;
+
+/**
+ * A global "Immutable" namespace used by UMD modules which allows the use of
+ * the full Immutable API.
+ *
+ * If using Immutable as an imported module, prefer using:
+ *
+ *     import Immutable from 'immutable'
+ *
+ */
+export as namespace Immutable;
