code: def tearDownClass(cls):
      ray.shutdown()
  
imports: import itertools
  import unittest
  import gymnasium
  import numpy
  import tree
  import ray
  from ray.rllib import SampleBatch
  from ray.rllib.algorithms.ppo.ppo_catalog import PPOCatalog
  from ray.rllib.algorithms.ppo.tf.ppo_tf_rl_module import PPOTfRLModule
  from ray.rllib.algorithms.ppo.torch.ppo_torch_rl_module import PPOTorchRLModule
  from ray.rllib.core.models.base import STATE_IN, STATE_OUT
  from ray.rllib.core.rl_module.rl_module import RLModuleConfig
  from ray.rllib.models.preprocessors import get_preprocessor
  from ray.rllib.utils.framework import try_import_tf, try_import_torch
  from ray.rllib.utils.numpy import convert_to_numpy
  from ray.rllib.utils.torch_utils import convert_to_torch_tensor
label_desc: Use image node_id 2 for calling the TestPPO obj's underlying member method code with example usage: obj.tearDownClass(cls) without return types