code: def _add_gateway_responses(self):
          
  
          if not self.gateway_responses:
              return
  
          if self.gateway_responses and not self.definition_body:
              raise InvalidResourceException(
                  self.logical_id, "GatewayResponses works only with inline Swagger specified in "
                                   "'DefinitionBody' property")
  
          # Make sure keys in the dict are recognized
          for responses_key, responses_value in self.gateway_responses.items():
              for response_key in responses_value.keys():
                  if response_key not in GatewayResponseProperties:
                      raise InvalidResourceException(
                          self.logical_id,
                          "Invalid property '{}' in 'GatewayResponses' property '{}'".format(response_key, responses_key))
  
          if not SwaggerEditor.is_valid(self.definition_body):
              raise InvalidResourceException(
                  self.logical_id, "Unable to add Auth configuration because "
                                   "'DefinitionBody' does not contain a valid Swagger")
  
          swagger_editor = SwaggerEditor(self.definition_body)
  
          gateway_responses = {}
          for response_type, response in self.gateway_responses.items():
              gateway_responses[response_type] = ApiGatewayResponse(
                  api_logical_id=self.logical_id,
                  response_parameters=response.get('ResponseParameters', {}),
                  response_templates=response.get('ResponseTemplates', {}),
                  status_code=response.get('StatusCode', None)
              )
  
          if gateway_responses:
              swagger_editor.add_gateway_responses(gateway_responses)
  
          # Assign the Swagger back to template
          self.definition_body = swagger_editor.swagger
docs: Add Gateway Response configuration to the Swagger file, if necessary