code: def testUpdates(self):
      with ops.Graph().as_default() as g:
          a = constant_op.constant(10)
          b = constant_op.constant(20)
          c = a + b
          train_op = ops.get_collection_ref(ops.GraphKeys.TRAIN_OP)
          train_op.append(c)
          mg = meta_graph.create_meta_graph_def(graph=g)
          grappler_item = item.Item(mg)
  
      initial_tf_item = grappler_item.tf_item
      no_change_tf_item = grappler_item.tf_item
      self.assertEqual(initial_tf_item, no_change_tf_item)
  
      # Modify the placement.
      for node in grappler_item.metagraph.graph_def.node:
          node.device = "/cpu:0"
      new_tf_item = grappler_item.tf_item
      self.assertNotEqual(initial_tf_item, new_tf_item)
  
      # Assign the same placement.
      for node in grappler_item.metagraph.graph_def.node:
          node.device = "/cpu:0"
      newest_tf_item = grappler_item.tf_item
      self.assertEqual(new_tf_item, newest_tf_item)
  
file_path: tensorflow/tensorflow/python/grappler/item_test.py
imports: from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import errors_impl
  from tensorflow.python.framework import meta_graph
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import tensor_shape
  from tensorflow.python.framework import test_util
  from tensorflow.python.grappler import item
  from tensorflow.python.ops import control_flow_ops
  from tensorflow.python.ops import gen_array_ops
  from tensorflow.python.ops import state_ops
  from tensorflow.python.ops import variable_v1
  from tensorflow.python.platform import test
label_desc: Use image node_id 4 for calling the ItemTest obj's underlying member method code with example usage: obj.testUpdates() without return types