code: def test_op_removed(self):
      x = theano.tensor.matrix("x")
      y = x * gradient.disconnected_grad(x)
      f = theano.function([x], y)
      # need to refer to theano.gradient.disconnected_grad here,
      # theano.gradient.disconnected_grad is a wrapper function!
      assert gradient.disconnected_grad_ not in [
          node.op for node in f.maker.fgraph.toposort()
      ]
  
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 2 for calling the TestDisconnectedGrad obj's underlying member method code with example usage: obj.test_op_removed() without return types