code: def test_merge_only(self):
      # Test `is_same_graph` when `equal_computations` cannot be used.
  
      x, y, z = tensor.vectors("x", "y", "z")
      t = x * y
      self.check(
          [
              (x, t, (({}, False), ({t: x}, True))),
              (
                  t * 2,
                  x * 2,
                  (
                      ({}, False),
                      ({t: x}, True),
                  ),
              ),
              (
                  x * x,
                  x * y,
                  (
                      ({}, False),
                      ({y: x}, True),
                  ),
              ),
              (
                  x * x,
                  x * y,
                  (
                      ({}, False),
                      ({y: x}, True),
                  ),
              ),
              (
                  x * x + z,
                  x * y + t,
                  (({}, False), ({y: x}, False), ({y: x, t: z}, True)),
              ),
          ],
          debug=False,
      )
  
imports: from __future__ import absolute_import, print_function, division
  from itertools import count
  import pickle
  import unittest
  from nose.plugins.skip import SkipTest
  import numpy
  from theano import sparse, shared, tensor
  from theano.gof.graph import Apply, as_string, clone, general_toposort, inputs, io_toposort, is_same_graph, Variable
  from theano.gof.op import Op
  from theano.gof.type import Type
label_desc: Use image node_id 4 for calling the TestIsSameGraph obj's underlying member method code with example usage: obj.test_merge_only() without return types