code: def test_type_check(self):
      x = chainer.Variable(self._rand())
      y = x * x
      y.grad = self._rand()
      gy = chainer.Variable(self._rand())
  
      with self.assertRaises(TypeError):
          chainer.backward(y)
      with self.assertRaises(TypeError):
          chainer.backward([y], gy)
  
      chainer.backward([y])
      chainer.backward([y], [gy])
  
imports: import unittest
  import mock
  import numpy
  import pytest
  import chainer
  from chainer.backends import cuda
  from chainer import testing
  from chainer.testing import attr
  import chainerx
label_desc: Use image node_id 2 for calling the TestBackwardTypeCheck obj's underlying member method code with example usage: obj.test_type_check() without return types