code: def test_unimplemented_grad_func(self):
      # tests that function compilation catches unimplemented grads
      # in the graph
  
      a = theano.tensor.vector()
      b = theano.gradient.grad_not_implemented(theano.tensor.add, 0, a)
      self.assertRaises(
          TypeError, theano.function, [a], b, on_unused_input="ignore"
      )
  
imports: from __future__ import absolute_import, print_function, division
  from collections import OrderedDict
  import unittest
  import numpy
  from six.moves import xrange
  import theano
  from theano import gof, change_flags
  from theano.compat import izip
  from theano.tests import unittest_tools
  from theano import gradient
  from theano import config
  from theano.gof.null_type import NullType
  from theano.sandbox.rng_mrg import MRG_RandomStreams
label_desc: Use image node_id 1 for calling the test_grad obj's underlying member method code with example usage: obj.test_unimplemented_grad_func() without return types