class_docstr: Adds subTest() context manager to the TestCase if supported.
  
  Note: To use this feature, make sure you call super() in setUpClass to
  initialize the sub stack.
code: def setUpClass(cls):
      super(SubTestCase, cls).setUpClass()
      cls._sub_test_stack = []
  
imports: import contextlib
  import dataclasses
  import functools
  from typing import Any, Optional, Type
  import dill
  from etils import enp
  import numpy
  from tensorflow_datasets.core import dataset_utils
  from tensorflow_datasets.core import features
  from tensorflow_datasets.core import utils
  from tensorflow_datasets.core.data_sources import python
  from tensorflow_datasets.core.features import feature
  from tensorflow_datasets.core.utils import tree_utils
  from tensorflow_datasets.core.utils.lazy_imports_utils import tensorflow
  from tensorflow_datasets.testing import test_case
  from tensorflow_datasets.testing import test_utils
label_desc: Use image node_id 1 for calling the SubTestCase obj's underlying member method code with example usage: obj.setUpClass(cls) without return types