private function parseHeader($curl, $headers)
    {
        if (!$this->responseStatusLine && strpos($headers, 'HTTP/') === 0) {
            $this->responseStatusLine = $headers;
        } else {
            $parts = explode(': ', $headers);
            if (isset($parts[1])) {
                $this->responseHeaders[$parts[0]] = trim($parts[1]);
            }
        }
        return strlen($headers);
    }