public function files($rejectClosure = null)
    {
        // we need to filter files we don't support, lets use the collection
        $filesCollection = new Collection($this->disk->files($this->directory(), false));

        return $filesCollection->reject(function ($file) use ($rejectClosure) {
            // ensure the file ends with allowed extension
            $shouldReject = !preg_match('/.'.self::CHUNK_EXTENSION.'$/', $file);
            if ($shouldReject) {
                return true;
            }
            if (is_callable($rejectClosure)) {
                return $rejectClosure($file);
            }

            return false;
        });
    }