code: def setUp(self):
      self.communicator = chainermn.create_communicator("naive")
  
      if self.communicator.size < 2:
          pytest.skip("This test is for multinode only")
  
      N = 100
      self.dataset = np.arange(N).astype(np.float32)
  
file_path: chainer/tests/chainermn_tests/iterators_tests/test_synchronized_iterator.py
imports: import chainer
  import chainer.testing
  import chainermn
  import numpy
  import pytest
  import unittest
label_desc: Use image node_id 1 for calling the TestSynchronizedIterator obj's underlying member method code with example usage: obj.setUp() without return types