code: def test_graph_item_context_scope():
      g1 = ops.Graph()
      i1 = graph_item.GraphItem(graph=g1)
      assert graph_item._default_graph_item is None
      with i1.as_default() as item:
          assert graph_item._default_graph_item == i1
          assert item._graph == g1
          assert ops.get_default_graph() == g1
          setattr(item, "new_attr", "new_value")
      assert graph_item._default_graph_item is None
      assert getattr(i1, "new_attr") == "new_value"
  
file_path: autodist/tests/test_graph_item.py
imports: import numpy
  import pytest
  import tensorflow
  from tensorflow.python import ops
  from tensorflow.python.keras.optimizer_v2 import adadelta
  from tensorflow.python.keras.optimizer_v2 import adagrad
  from tensorflow.python.keras.optimizer_v2 import adam
  from tensorflow.python.keras.optimizer_v2 import adamax
  from tensorflow.python.keras.optimizer_v2 import ftrl
  from tensorflow.python.keras.optimizer_v2 import gradient_descent
  from tensorflow.python.keras.optimizer_v2 import nadam
  from tensorflow.python.keras.optimizer_v2 import rmsprop
  from tensorflow.python.training.training_util import get_or_create_global_step
  from autodist import graph_item
  from autodist.kernel.common.op_info import UPDATE_OP_VAR_POS
label_desc: Use image node_id 4 for calling a global function with example usage: test_graph_item_context_scope() without return types