code: def tearDownClass(cls) -> None:
      ray.shutdown()
  
file_path: ray/rllib_contrib/qmix/tests/test_qmix.py
imports: import unittest
  import numpy
  from gymnasium.spaces import Box, Dict, Discrete, MultiDiscrete, Tuple
  from rllib_qmix.qmix import QMixConfig
  import ray
  from ray.rllib.env.multi_agent_env import MultiAgentEnv
  from ray.tune import register_env
label_desc: Use image node_id 2 for calling the TestQMix obj's underlying member method code with example usage: obj.tearDownClass(cls) without return types