App\services\RESTfulService::__construct PHP Method

    public function __construct($key, $secret, $endpoint, Client $client)
    {
        $this->setKey($key);
        $this->setSecret($secret);
        $this->setEndpoint($endpoint);
        $this->setClient($client);
    }

 /**
  * Construct an instance of YouTube service.
  *
  * @param string      $key    The YouTube API key
  * @param Client|null $client The Guzzle HTTP client
  */
 public function __construct($key = null, Client $client = null)
 {
     parent::__construct($key ?: config('koel.youtube.key'), null, 'https://www.googleapis.com/youtube/v3', $client ?: new Client());
 }