public function getMethod() :? int
  {
    switch($this->server('REQUEST_METHOD')) {
      case 'GET':
        return self::HTTP_GET;
      case 'POST':
        return self::HTTP_POST;
      case 'HEAD':
        return self::HTTP_HEAD;
      case 'PUT':
        return self::HTTP_PUT;
      case 'DELETE':
        return self::HTTP_DELETE;
      case 'TRACE':
        return self::HTTP_TRACE;
      case 'OPTIONS':
        return self::HTTP_OPTIONS;
      case 'CONNECT':
        return self::HTTP_CONNECT;
    }

    return null;
  }