code: def tearDown(cls) -> None:
      ray.shutdown()
  
imports: import gymnasium
  import numpy
  import tempfile
  import unittest
  import ray
  from ray.rllib.core.learner.learner import Learner
  from ray.rllib.core.testing.testing_learner import BaseTestingAlgorithmConfig
  from ray.rllib.policy.sample_batch import DEFAULT_POLICY_ID
  from ray.rllib.utils.numpy import convert_to_numpy
  from ray.rllib.utils.framework import try_import_tf, try_import_torch
  from ray.rllib.utils.test_utils import check, framework_iterator, get_cartpole_dataset_reader
  from ray.rllib.utils.metrics import ALL_MODULES
label_desc: Use image node_id 2 for calling the TestLearner obj's underlying member method code with example usage: obj.tearDown(cls) without return types