public function request($url)
    {
        $ch = curl_init();

        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, $this->timeout);

        $response = curl_exec($ch);

        curl_close($ch);

        if ($response === false) {
            throw new \RuntimeException('Connection timeout.');
        }

        return $response;
    }