Flow\File::__construct PHP Method

    public function __construct(ConfigInterface $config, RequestInterface $request = null)
    {
        $this->config = $config;
        if ($request === null) {
            $request = new Request();
        }
        $this->request = $request;
        $this->identifier = call_user_func($this->config->getHashNameCallback(), $request);
    }

 function __construct(MongoConfigInterface $config, RequestInterface $request = null)
 {
     if ($request === null) {
         $request = new Request();
     }
     parent::__construct($config, $request);
     $this->config = $config;
 }