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// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
import { Selector } from "./types.ts";
/** * Returns all elements in the given array that produce a distinct value using the given selector, preserving order by first occurence * * Example: * * ```typescript * const names = [ 'Anna', 'Kim', 'Arnold', 'Kate' ] * const exampleNamesByFirstLetter = distinctBy(names, it => it.charAt(0)) * * console.assert(exampleNamesByFirstLetter === [ 'Anna', 'Kim' ]) * ``` */export function distinctBy<T, D>(  array: Array<T>,  selector: Selector<T, D>,): Array<T> {  const selectedValues = new Set<D>();  const ret = new Array<T>();
  for (const element of array) {    const currentSelectedValue = selector(element);
    if (!selectedValues.has(currentSelectedValue)) {      selectedValues.add(currentSelectedValue);      ret.push(element);    }  }
  return ret;}