code: def tearDown(cls) -> None:
      ray.shutdown()
  
imports: import gymnasium
  import itertools
  import numpy
  from typing import Any, Dict, List
  import tempfile
  import unittest
  import ray
  from ray.rllib.algorithms.algorithm_config import AlgorithmConfig
  from ray.rllib.algorithms.ppo.tests.test_ppo_learner import FAKE_BATCH
  from ray.rllib.core.learner.learner import Learner
  from ray.rllib.core.rl_module.marl_module import MultiAgentRLModule
  from ray.rllib.core.rl_module.rl_module import SingleAgentRLModuleSpec
  from ray.rllib.core.testing.tf.bc_learner import BCTfLearner
  from ray.rllib.core.testing.tf.bc_module import DiscreteBCTFModule
  from ray.rllib.core.testing.utils import add_module_to_learner_or_learner_group
  from ray.rllib.core.testing.testing_learner import BaseTestingAlgorithmConfig
  from ray.rllib.examples.env.multi_agent import MultiAgentCartPole
  from ray.rllib.policy.sample_batch import DEFAULT_POLICY_ID, SampleBatch, MultiAgentBatch
  from ray.rllib.utils.test_utils import check, get_cartpole_dataset_reader
  from ray.rllib.utils.metrics import ALL_MODULES
  from ray.util.timer import _Timer
label_desc: Use image node_id 2 for calling the TestLearnerGroupAsyncUpdate obj's underlying member method code with example usage: obj.tearDown(cls) without return types