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// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
/** Options for {@linkcode getAvailablePort}. */export interface GetAvailablePortOptions {  /**   * A port to check availability of first. If the port isn't available, fall   * back to another port.   */  preferredPort?: number;}
/** * Returns an available network port. * * @example * ```ts * import { getAvailablePort } from "https://deno.land/std@$STD_VERSION/net/get_available_port.ts"; * * const port = getAvailablePort(); * Deno.serve({ port }, () => new Response("Hello, world!")); * ``` */export function getAvailablePort(options?: GetAvailablePortOptions): number {  if (options?.preferredPort) {    try {      // Check if the preferred port is available      using listener = Deno.listen({ port: options.preferredPort });      return listener.addr.port;    } catch (e) {      // If the preferred port is not available, fall through and find an available port      if (!(e instanceof Deno.errors.AddrInUse)) {        throw e;      }    }  }
  using listener = Deno.listen({ port: 0 });  return listener.addr.port;}