code: def setUp(self):
      self.communicator = chainermn.create_communicator("naive")
  
      # Use CuPy's Device class to foce call cudaSetDevice()
      if chainer.backends.cuda.available:
          chainer.cuda.get_device_from_id(
              self.communicator.intra_rank
          ).use()
  
imports: import unittest
  import chainer
  import chainer.testing
  import chainer.testing.attr
  import chainermn
  from chainermn.testing.device import get_device
label_desc: Use image node_id 1 for calling the TestCreateMnBnModel obj's underlying member method code with example usage: obj.setUp() without return types