code: def test_deserialize_none(self):
      self.assertIs(self.from_json(None, self.dummy_manager), None)
  
imports: import array
  import datetime
  import pytest
  from unittest import TestCase
  from traitlets import HasTraits, Int, TraitError
  from traitlets.tests.test_traitlets import TraitTestBase
  from ipywidgets import Color, NumberFormat
  from ipywidgets.widgets.widget import _remove_buffers, _put_buffers
  from ipywidgets.widgets.trait_types import date_serialization, TypedTuple
label_desc: Use image node_id 2 for calling the TestDateDeserialization obj's underlying member method code with example usage: obj.test_deserialize_none() without return types