public function register(Container $app)
    {
        $app['guzzle.handler_stack'] = function () {
            $stack = HandlerStack::create();

            return $stack;
        };

        $app['guzzle'] = function () use ($app) {
            $client = new HttpClient([
                'handler' => $app['guzzle.handler_stack']
            ]);

            return $client;
        };
    }