protected function send($content)
    {
        $url = sprintf('https://%s/%s/%s/%s', self::HOST, self::ROOMS_ENDPOINT, $this->roomId, self::MESSAGES_ENDPOINT);
        $data = json_encode(array('text' => $content));
        $headers = array(
            'Content-Type: application/json',
            'Accept: application/json',
            "Authorization: Bearer {$this->token}"
        );

        $ch = curl_init();

        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_POST, true);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
        curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

        curl_exec($ch);
        curl_close($ch);
    }