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// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.// This module is browser compatible.
/** * Returns an element if and only if that element is the only one matching the * given condition. Returns `undefined` otherwise. * * @example * ```ts * import { findSingle } from "https://deno.land/std@$STD_VERSION/collections/find_single.ts"; * import { assertEquals } from "https://deno.land/std@$STD_VERSION/testing/asserts.ts"; * * const bookings = [ *   { month: "January", active: false }, *   { month: "March", active: false }, *   { month: "June", active: true }, * ]; * const activeBooking = findSingle(bookings, (it) => it.active); * const inactiveBooking = findSingle(bookings, (it) => !it.active); * * assertEquals(activeBooking, { month: "June", active: true }); * assertEquals(inactiveBooking, undefined); // there are two applicable items * ``` */export function findSingle<T>(  array: readonly T[],  predicate: (el: T) => boolean,): T | undefined {  let match: T | undefined = undefined;  let found = false;  for (const element of array) {    if (predicate(element)) {      if (found) {        return undefined;      }      found = true;      match = element;    }  }
  return match;}