Index: node_modules/es-toolkit/dist/math/sumBy.d.mts
===================================================================
--- node_modules/es-toolkit/dist/math/sumBy.d.mts	(revision a762898ecd37a452c782821d4c2c4955c6ed2521)
+++ node_modules/es-toolkit/dist/math/sumBy.d.mts	(revision a762898ecd37a452c782821d4c2c4955c6ed2521)
@@ -0,0 +1,19 @@
+/**
+ * Calculates the sum of an array of numbers when applying
+ * the `getValue` function to each element.
+ *
+ * If the array is empty, this function returns `0`.
+ *
+ * @template T - The type of elements in the array.
+ * @param {readonly T[]} items - An array to calculate the sum.
+ * @param {(element: T, index: number) => number} getValue - A function that selects a numeric value from each element.
+ *   It receives the element and its zero‑based index in the array.
+ * @returns {number} The sum of all the numbers as determined by the `getValue` function.
+ *
+ * @example
+ * sumBy([{ a: 1 }, { a: 2 }, { a: 3 }], (x, i) => x.a * i); // Returns: 8
+ * sumBy([], () => 1); // Returns: 0
+ */
+declare function sumBy<T>(items: readonly T[], getValue: (element: T, index: number) => number): number;
+
+export { sumBy };