code: def tearDownClass(cls):
      ray.shutdown()
  
imports: import unittest
  import tempfile
  import gymnasium
  import numpy
  import tensorflow
  import torch
  import tree
  import ray
  import ray.rllib.algorithms.ppo
  from ray.rllib.algorithms.ppo.ppo import LEARNER_RESULTS_CURR_KL_COEFF_KEY
  from ray.rllib.examples.env.multi_agent import MultiAgentCartPole
  from ray.rllib.policy.sample_batch import SampleBatch
  from ray.tune.registry import register_env
  from ray.rllib.utils.metrics.learner_info import LEARNER_INFO
  from ray.rllib.utils.test_utils import check, framework_iterator
  from ray.rllib.evaluation.postprocessing import compute_gae_for_sample_batch
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