code: def setUp(self):
      self.mpi_comm = mpi4py.MPI.COMM_WORLD
      self.communicator = NaiveCommunicator(self.mpi_comm)
  
file_path: chainer/tests/chainermn_tests/communicator_tests/test_communication_utility.py
imports: import mpi4py
  import numpy
  import pytest
  import unittest
  from chainermn.communicators._communication_utility import chunked_bcast_obj
  from chainermn.communicators._communication_utility import INT_MAX
  from chainermn.communicators.naive_communicator import NaiveCommunicator
label_desc: Use image node_id 1 for calling the TestCommunicationUtility obj's underlying member method code with example usage: obj.setUp() without return types