code: def check_backward(self, x_data, y_grad):
      if self.nobias:
          params = self.link.deform_conv.W
      else:
          params = (self.link.deform_conv.W, self.link.deform_conv.b)
  
      gradient_check.check_backward(
          self.link,
          x_data,
          y_grad,
          params,
          eps=2**-3,
          atol=1e-3,
          rtol=1e-3,
      )
  
file_path: chainer/tests/chainer_tests/links_tests/connection_tests/test_deformable_convolution_2d.py
imports: import unittest
  import numpy
  from chainer.backends import cuda
  from chainer import gradient_check
  from chainer import links
  from chainer import testing
  from chainer.testing import attr
  from chainer.testing import condition
  from chainer import utils
label_desc: Use image node_id 2 for calling the TestDeformableConvolution2D obj's underlying member method code with example usage: obj.check_backward(x_data, y_grad) without return types