code: def _check_response_for_request_errors(self):
          
  
          if self.response.HighestSeverity == "ERROR":
              for notification in self.response.Notifications:
                  if notification.Severity == "ERROR":
                      raise FedexError(notification.Code,
                                       notification.Message)
docs: Override this in each service module to check for errors that are
          specific to that module. For example, invalid tracking numbers in
          a Tracking request.