code: def fail(self, tup_id):
          
          saved_args = self.unacked_tuples.get(tup_id)
          if saved_args is None:
              self.logger.error("Received fail for unknown tuple ID: %r", tup_id)
              return
          tup, stream, direct_task, need_task_ids = saved_args
          if self.failed_tuples[tup_id] < self.max_fails:
              self.emit(
                  tup,
                  tup_id=tup_id,
                  stream=stream,
                  direct_task=direct_task,
                  need_task_ids=need_task_ids,
              )
              self.failed_tuples[tup_id] += 1
          else:
              # Just pretend we got an ack when we exceed retry limit
              self.logger.info(
                  "Acking tuple ID %r after it exceeded retry limit " "(%r)",
                  tup_id,
                  self.max_fails,
              )
              self.ack(tup_id)
docs: Called when a Tuple fails in the topology
  
          A reliable spout will replay a failed tuple up to ``max_fails`` times.
  
          :param tup_id: the ID of the Tuple that has failed in the topology
                         either due to a bolt calling ``fail()`` or a Tuple
                         timing out.
          :type tup_id: str