code: def test_inherit_parent_default_value(self):
      lit_type = types.SingleFieldMatcher(
          spec="dataset", types=["LitType"]
      )
      self.assertIsNone(lit_type.default)
  
imports: from collections.abc import Callable
  import os
  from typing import Any, Optional, Union
  from absl.testing import absltest
  from absl.testing import parameterized
  from etils import epath
  from lit_nlp.api import dtypes
  from lit_nlp.api import types
  import numpy
label_desc: Use image node_id 2 for calling the TypesTest obj's underlying member method code with example usage: obj.test_inherit_parent_default_value() without return types