public function getResponseHeader($name = null, $first = true)
    {
        // Return response header string when parameter is not provided
        if (is_null($name)) {
            return $this->responseHeader;
        }

        $name = strtoupper($name);
        $headers = $this->getResponseHeaders();

        if (!isset($headers[$name])) {
            return $first ? null : array();
        } else {
            return $first ? current($headers[$name]) : $headers[$name];
        }
    }