protected function get($url)
    {
        $request = $this->http->get(
            $url,
            array('User-Agent' => self::USER_AGENT.' v.'.self::VERSION)
        );

        $response = $request->send();

        if (!$response->isSuccessful()) {
            $this->log('fail with '.$response->getStatusCode().' http code in url "'.$url.'" ');

            return;
        }
        $this->logger->log(LogLevel::INFO, 'retrieved url "'.$url.'" ');

        return $response->getBody();
    }