code: def _rpc(http, project, method, base_url, request_pb, response_pb_cls):
      
      req_data = request_pb.SerializeToString()
      response = _request(http, project, method, req_data, base_url)
      return response_pb_cls.FromString(response)
docs: Make a protobuf RPC request.
  
      :type http: :class:`requests.Session`
      :param http: HTTP object to make requests.
  
      :type project: str
      :param project: The project to connect to. This is
                      usually your project name in the cloud console.
  
      :type method: str
      :param method: The name of the method to invoke.
  
      :type base_url: str
      :param base_url: The base URL where the API lives.
  
      :type request_pb: :class:`google.protobuf.message.Message` instance
      :param request_pb: the protobuf instance representing the request.
  
      :type response_pb_cls: A :class:`google.protobuf.message.Message`
                             subclass.
      :param response_pb_cls: The class used to unmarshall the response
                              protobuf.
  
      :rtype: :class:`google.protobuf.message.Message`
      :returns: The RPC message parsed from the response.