code: def check_backward(self, input_data, grad_data):
      func = self.make_func()
      gradient_check.check_backward(
          func, input_data, grad_data, **self.backward_test_options
      )
  
imports: import unittest
  import warnings
  import numpy
  import pytest
  import chainer
  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
label_desc: Use image node_id 7 for calling the TheanoFunctionTestBase obj's underlying member method code with example usage: obj.check_backward(input_data, grad_data) without return types