code: def test_grad_half(self):
      # It is not implemented for now. So test that we raise an error.
      shape = (2, 3, 6, 6)
      images_val = np.random.rand(*shape).astype("float32")
  
      def fn(images):
          return images2neibs(images, (3, 3), mode="half")
  
      self.assertRaises(
          TypeError,
          unittest_tools.verify_grad,
          fn,
          [images_val],
          mode=self.mode,
      )
  
imports: from __future__ import absolute_import, print_function, division
  import numpy
  import unittest
  import theano
  from theano import shared, function
  import theano.tensor
  from theano.tensor.nnet.neighbours import images2neibs, neibs2images, Images2Neibs
  from theano.tests import unittest_tools
  from theano import change_flags
label_desc: Use image node_id 10 for calling the T_Images2Neibs obj's underlying member method code with example usage: obj.test_grad_half() and returns: images2neibs