code: def test_backward_chainerx(self):
      self.check_backward(
          [chainerx.array(x) for x in self.xs], chainerx.array(self.g)
      )
  
imports: import unittest
  import numpy
  import chainer
  from chainer import backend
  from chainer.backends import cuda
  from chainer import functions
  from chainer import gradient_check
  from chainer import testing
  from chainer.testing import attr
  import chainerx
label_desc: Use image node_id 9 for calling the TestStack obj's underlying member method code with example usage: obj.test_backward_chainerx() without return types