code: def serialize(self, serializer):
      # Master's and Slave's serialize must be called at the same time.
      self.actual_iterator.serialize(serializer)
      self.communicator.bcast_obj(serializer, root=self.rank_master)
  
imports: import chainer
  import numpy
label_desc: Use image node_id 8 for calling the _MultiNodeIteratorMaster obj's underlying member method code with example usage: obj.serialize(serializer) without return types