code: def setUp(self):
      self.communicator = chainermn.create_communicator("naive")
  
      if self.communicator.size < 2:
          pytest.skip("This test is for multinode only")
  
imports: import chainer
  import chainer.testing
  import chainer.testing.attr
  import chainermn
  from chainermn.iterators.multi_node_iterator import _build_ctrl_msg
  from chainermn.iterators.multi_node_iterator import _parse_ctrl_msg
  import numpy
  import platform
  import pytest
  from six.moves import range
  import unittest
label_desc: Use image node_id 1 for calling the TestMultiNodeIteratorDataType obj's underlying member method code with example usage: obj.setUp() without return types