code: def send(self, task, result, expire=60):
          
          self.rdb.lpush(task.urn, json.dumps(result))
          self.rdb.expire(task.urn, expire)
docs: Sends the result back to the producer. This should be called if only you
          want to return the result in async manner.
  
          :arg task: ::class:`~retask.task.Task` object
          :arg result: Result data to be send back. Should be in JSON serializable.
          :arg expire: Time in seconds after the key expires. Default is 60 seconds.