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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.// This module is browser compatible.
/** * Applies the given transformer to all keys in the given record's entries and returns a new record containing the * transformed entries. * * If the transformed entries contain the same key multiple times, only the last one will appear in the returned record. * * Example: * * ```ts * import { mapKeys } from "https://deno.land/std@$STD_VERSION/collections/map_keys.ts"; * import { assertEquals } from "https://deno.land/std@$STD_VERSION/testing/asserts.ts"; * * const counts = { a: 5, b: 3, c: 8 } * * assertEquals(mapKeys(counts, it => it.toUpperCase()), { *     A: 5, *     B: 3, *     C: 8, * }) * ``` */export function mapKeys<T>(  record: Readonly<Record<string, T>>,  transformer: (key: string) => string,): Record<string, T> {  const ret: Record<string, T> = {};  const keys = Object.keys(record);
  for (const key of keys) {    const mappedKey = transformer(key);
    ret[mappedKey] = record[key];  }
  return ret;}