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// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.// This module is browser compatible.
/** * Returns all elements in the given array that produce a distinct value using * the given selector, preserving order by first occurrence. * * @example * ```ts * import { distinctBy } from "https://deno.land/std@$STD_VERSION/collections/distinct_by.ts"; * import { assertEquals } from "https://deno.land/std@$STD_VERSION/testing/asserts.ts"; * * const names = ["Anna", "Kim", "Arnold", "Kate"]; * const exampleNamesByFirstLetter = distinctBy(names, (it) => it.charAt(0)); * * assertEquals(exampleNamesByFirstLetter, ["Anna", "Kim"]); * ``` */export function distinctBy<T, D>(  array: readonly T[],  selector: (el: T) => D,): T[] {  const selectedValues = new Set<D>();  const ret: T[] = [];
  for (const element of array) {    const currentSelectedValue = selector(element);
    if (!selectedValues.has(currentSelectedValue)) {      selectedValues.add(currentSelectedValue);      ret.push(element);    }  }
  return ret;}