public static function getGuzzleClient()
    {
        if (!isset(self::$guzzleClient) || is_null(self::$guzzleClient)) {
            self::$guzzleClient = new Client(array('timeout' => Config::TIMEOUT, 'connection_timeout' => Config::CONN_TIMEOUT, 'verify' => Config::$IS_LIVE));
        }

        return self::$guzzleClient;
    }