code: def test_backward_cpu(self):
      self.check_backward(self.x, self.gy)
  
file_path: chainer/tests/chainer_tests/links_tests/connection_tests/test_inception.py
imports: import unittest
  import numpy
  import chainer
  from chainer.backends import cuda
  from chainer import links
  from chainer import testing
  from chainer.testing import attr
label_desc: Use image node_id 3 for calling the TestInception obj's underlying member method code with example usage: obj.test_backward_cpu() without return types