code: def tearDownClass(cls):
      ray.shutdown()
  
imports: import os
  from pathlib import Path
  from packaging import version
  import sys
  import unittest
  import ray
  import ray.cloudpickle
  from ray.rllib.algorithms.algorithm import Algorithm
  from ray.rllib.algorithms.algorithm_config import AlgorithmConfig
  from ray.rllib.algorithms.dqn import DQN
  from ray.rllib.algorithms.ppo import PPO
  from ray.rllib.examples.env.multi_agent import MultiAgentCartPole
  from ray.rllib.policy.policy import Policy, PolicySpec
  from ray.rllib.utils.checkpoints import get_checkpoint_info
  from ray.rllib.utils.test_utils import framework_iterator
  from ray.tune.registry import register_env
label_desc: Use image node_id 2 for calling the TestBackwardCompatibility obj's underlying member method code with example usage: obj.tearDownClass(cls) without return types