code: def _cleanup_workflow(config, task_id, args, **kwargs):
      
      from lightflow.models import Workflow
      if isinstance(args[0], Workflow):
          if config.celery['result_expires'] == 0:
              AsyncResult(task_id).forget()
docs: Cleanup the results of a workflow when it finished.
  
      Connects to the postrun signal of Celery. If the signal was sent by a workflow,
      remove the result from the result backend.
  
      Args:
          task_id (str): The id of the task.
          args (tuple): The arguments the task was started with.
          **kwargs: Keyword arguments from the hook.