Get the result of file exist/no exits

test.php

<?php
	use app\clFilesystem;
	use React\MySQL\Factory;

	require __DIR__ . '/vendor/autoload.php';
	
	$loop = React\EventLoop\Factory::create();
		$filesystem = \React\Filesystem\Filesystem::create($loop);

		$file = "teste.txt";
		f_existsFile($filesystem, $file)->then(function (string $result) use ($file) {
			echo 'The file ['.$file.'] ['.$result."]\n";
		});

//----- Final do LOOP
$loop->run();
// F U N C T I O N ////////////////////////////////////////////////////
/** @return \React\Promise\PromiseInterface<string> */
function f_existsFile($filesystem, $file): \React\Promise\PromiseInterface
{
   return $filesystem->file($file)->exists()->then(function () {
      return 'exists';
   }, function () {
      return 'was not found';
   });
}
?>