code: def _handle_stop_dag(self, request):
          
          if (request.payload['name'] is not None) and \
             (request.payload['name'] not in self._stop_dags):
              self._stop_dags.append(request.payload['name'])
          return Response(success=True, uid=request.uid)
docs: The handler for the stop_dag request.
  
          The stop_dag request adds a dag to the list of dags that should be stopped.
          The dag will then stop queueing new tasks and will eventually stop running.
  
          Args:
              request (Request): Reference to a request object containing the
                                 incoming request. The payload has to contain the
                                 following fields:
                                  'name': the name of the dag that should be stopped
  
          Returns:
              Response: A response object containing the following fields:
                            - success: True if the dag was added successfully to the list
                                       of dags that should be stopped.