code: def tearDownClass(cls):
      ray.shutdown()
  
imports: import tempfile
  import unittest
  import ray
  from ray.rllib.algorithms.appo import APPOConfig
  from ray.rllib.algorithms.callbacks import DefaultCallbacks
  from ray.rllib.algorithms.ppo import PPOConfig
  from ray.rllib.examples.env.cartpole_crashing import CartPoleCrashing
  from ray.rllib.utils.test_utils import framework_iterator
  from ray import tune
label_desc: Use image node_id 2 for calling the TestCallbacks obj's underlying member method code with example usage: obj.tearDownClass(cls) without return types