code: def check_backward(self, x_data, y_grad):
      xp = backend.get_array_module(x_data)
  
      if not self.c_contiguous:
          x_data = xp.asfortranarray(x_data)
          y_grad = xp.asfortranarray(y_grad)
          self.assertFalse(x_data.flags.c_contiguous)
          self.assertFalse(y_grad.flags.c_contiguous)
  
      gradient_check.check_backward(
          lambda x: shift.shift(
              x, ksize=self.ksize, dilate=self.dilate
          ),
          x_data,
          y_grad,
          dtype="d",
          atol=5e-4,
          rtol=5e-3,
      )
  
file_path: chainer/tests/chainer_tests/functions_tests/connection_tests/test_shift.py
imports: import unittest
  import numpy
  import chainer
  from chainer import backend
  from chainer.backends import cuda
  from chainer import gradient_check
  from chainer import testing
  from chainer.testing import attr
  from chainer.testing import condition
  from chainer.functions.connection import shift
label_desc: Use image node_id 3 for calling the TestShiftFunction obj's underlying member method code with example usage: obj.check_backward(x_data, y_grad) without return types