Index: node_modules/d3-selection/src/selection/data.js
===================================================================
--- node_modules/d3-selection/src/selection/data.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
+++ node_modules/d3-selection/src/selection/data.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
@@ -0,0 +1,128 @@
+import {Selection} from "./index.js";
+import {EnterNode} from "./enter.js";
+import constant from "../constant.js";
+
+function bindIndex(parent, group, enter, update, exit, data) {
+  var i = 0,
+      node,
+      groupLength = group.length,
+      dataLength = data.length;
+
+  // Put any non-null nodes that fit into update.
+  // Put any null nodes into enter.
+  // Put any remaining data into enter.
+  for (; i < dataLength; ++i) {
+    if (node = group[i]) {
+      node.__data__ = data[i];
+      update[i] = node;
+    } else {
+      enter[i] = new EnterNode(parent, data[i]);
+    }
+  }
+
+  // Put any non-null nodes that don’t fit into exit.
+  for (; i < groupLength; ++i) {
+    if (node = group[i]) {
+      exit[i] = node;
+    }
+  }
+}
+
+function bindKey(parent, group, enter, update, exit, data, key) {
+  var i,
+      node,
+      nodeByKeyValue = new Map,
+      groupLength = group.length,
+      dataLength = data.length,
+      keyValues = new Array(groupLength),
+      keyValue;
+
+  // Compute the key for each node.
+  // If multiple nodes have the same key, the duplicates are added to exit.
+  for (i = 0; i < groupLength; ++i) {
+    if (node = group[i]) {
+      keyValues[i] = keyValue = key.call(node, node.__data__, i, group) + "";
+      if (nodeByKeyValue.has(keyValue)) {
+        exit[i] = node;
+      } else {
+        nodeByKeyValue.set(keyValue, node);
+      }
+    }
+  }
+
+  // Compute the key for each datum.
+  // If there a node associated with this key, join and add it to update.
+  // If there is not (or the key is a duplicate), add it to enter.
+  for (i = 0; i < dataLength; ++i) {
+    keyValue = key.call(parent, data[i], i, data) + "";
+    if (node = nodeByKeyValue.get(keyValue)) {
+      update[i] = node;
+      node.__data__ = data[i];
+      nodeByKeyValue.delete(keyValue);
+    } else {
+      enter[i] = new EnterNode(parent, data[i]);
+    }
+  }
+
+  // Add any remaining nodes that were not bound to data to exit.
+  for (i = 0; i < groupLength; ++i) {
+    if ((node = group[i]) && (nodeByKeyValue.get(keyValues[i]) === node)) {
+      exit[i] = node;
+    }
+  }
+}
+
+function datum(node) {
+  return node.__data__;
+}
+
+export default function(value, key) {
+  if (!arguments.length) return Array.from(this, datum);
+
+  var bind = key ? bindKey : bindIndex,
+      parents = this._parents,
+      groups = this._groups;
+
+  if (typeof value !== "function") value = constant(value);
+
+  for (var m = groups.length, update = new Array(m), enter = new Array(m), exit = new Array(m), j = 0; j < m; ++j) {
+    var parent = parents[j],
+        group = groups[j],
+        groupLength = group.length,
+        data = arraylike(value.call(parent, parent && parent.__data__, j, parents)),
+        dataLength = data.length,
+        enterGroup = enter[j] = new Array(dataLength),
+        updateGroup = update[j] = new Array(dataLength),
+        exitGroup = exit[j] = new Array(groupLength);
+
+    bind(parent, group, enterGroup, updateGroup, exitGroup, data, key);
+
+    // Now connect the enter nodes to their following update node, such that
+    // appendChild can insert the materialized enter node before this node,
+    // rather than at the end of the parent node.
+    for (var i0 = 0, i1 = 0, previous, next; i0 < dataLength; ++i0) {
+      if (previous = enterGroup[i0]) {
+        if (i0 >= i1) i1 = i0 + 1;
+        while (!(next = updateGroup[i1]) && ++i1 < dataLength);
+        previous._next = next || null;
+      }
+    }
+  }
+
+  update = new Selection(update, parents);
+  update._enter = enter;
+  update._exit = exit;
+  return update;
+}
+
+// Given some data, this returns an array-like view of it: an object that
+// exposes a length property and allows numeric indexing. Note that unlike
+// selectAll, this isn’t worried about “live” collections because the resulting
+// array will only be used briefly while data is being bound. (It is possible to
+// cause the data to change while iterating by using a key function, but please
+// don’t; we’d rather avoid a gratuitous copy.)
+function arraylike(data) {
+  return typeof data === "object" && "length" in data
+    ? data // Array, TypedArray, NodeList, array-like
+    : Array.from(data); // Map, Set, iterable, string, or anything else
+}