code: def test_networkxs_to_graphs_tuple_with_none_fields(self):
      graph_nx = nx.OrderedMultiDiGraph()
      data_dict = utils_np.networkx_to_data_dict(
          graph_nx, node_shape_hint=None, edge_shape_hint=None
      )
      self.assertEqual(None, data_dict["edges"])
      self.assertEqual(None, data_dict["globals"])
      self.assertEqual(None, data_dict["nodes"])
      graph_nx.add_node(0, features=None)
      data_dict = utils_np.networkx_to_data_dict(
          graph_nx, node_shape_hint=1, edge_shape_hint=None
      )
      self.assertEqual(None, data_dict["nodes"])
      graph_nx.add_edge(0, 0, features=None)
      data_dict = utils_np.networkx_to_data_dict(
          graph_nx, node_shape_hint=[1], edge_shape_hint=[1]
      )
      self.assertEqual(None, data_dict["edges"])
      graph_nx.graph["features"] = None
      utils_np.networkx_to_data_dict(graph_nx)
      self.assertEqual(None, data_dict["globals"])
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import itertools
  from absl.testing import parameterized
  from graph_nets import utils_np
  from graph_nets.tests import test_utils
  import networkx
  import numpy
  from six.moves import range
  import tensorflow
label_desc: Use image node_id 2 for calling the NetworkxConversionTest obj's underlying member method code with example usage: obj.test_networkxs_to_graphs_tuple_with_none_fields() without return types