code: def serialize(self, serializer):
      # Master's and Slave's serialize must be called at the same time.
      _serializer = self.communicator.bcast_obj(
          None, root=self.rank_master
      )
  
      self.current_position = serializer(
          "current_position",
          _serializer("current_position", self.current_position),
      )
      self.epoch = serializer("epoch", _serializer("epoch", self.epoch))
      self.is_new_epoch = serializer(
          "is_new_epoch", _serializer("is_new_epoch", self.is_new_epoch)
      )
  
      try:
          self._order = serializer(
              "order", _serializer("order", self._order)
          )
      except KeyError:
          pass
  
imports: import chainer
  import numpy
label_desc: Use image node_id 4 for calling the _MultiNodeIteratorSlave obj's underlying member method code with example usage: obj.serialize(serializer) without return types