code: def test_dxdx():
      # Tests that the gradient of a scalar with respect to itself is 1
      # I use an integer in this case because people keep changing this
      # gradient to be 0 on integers but according to our interpretation
      # of the gradient as defined in the Op contract, it should be 1.
      # If you feel the need to change this unit test you are probably
      # modifying the Op contract and should definitely get the approval
      # of multiple people on theano-dev.
  
      x = theano.tensor.iscalar()
      g = theano.tensor.grad(x, x)
  
      g = g.eval({x: 12})
  
      assert np.allclose(g, 1.0)
  
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 3 for calling a global function with example usage: test_dxdx() without return types