code: def testDumpsNestedClass(self):
      obj = _DefaultJsonableObject(_DefaultJsonableObject, None, None)
  
      json_text = json_utils.dumps(obj)
      self.assertEqual(
          (
              '{"__class__": "_DefaultJsonableObject", "__module__": "__main__",'
              ' "__tfx_object_type__": "jsonable", "a": {"__class__":'
              ' "_DefaultJsonableObject", "__module__": "__main__",'
              ' "__tfx_object_type__": "class"}, "b": null, "c": null}'
          ),
          json_text,
      )
  
      actual_obj = json_utils.loads(json_text)
      self.assertEqual(_DefaultJsonableObject, actual_obj.a)
      self.assertIsNone(actual_obj.b)
      self.assertIsNone(actual_obj.c)
  
file_path: tfx/tfx/utils/json_utils_test.py
imports: import tensorflow
  from tfx.proto import trainer_pb2
  from tfx.utils import deprecation_utils
  from tfx.utils import json_utils
label_desc: Use image node_id 3 for calling the JsonUtilsTest obj's underlying member method code with example usage: obj.testDumpsNestedClass() without return types