code: def tearDownClass(cls):
      ray.shutdown()
  
file_path: ray/rllib_contrib/ddppo/tests/test_ddppo.py
imports: import unittest
  import pytest
  from rllib_ddppo.ddppo import DDPPOConfig
  import ray
  from ray.rllib.policy.sample_batch import DEFAULT_POLICY_ID
  from ray.rllib.utils.metrics.learner_info import LEARNER_INFO, LEARNER_STATS_KEY
  from ray.rllib.utils.test_utils import check, check_compute_single_action, check_train_results, framework_iterator
label_desc: Use image node_id 2 for calling the TestDDPPO obj's underlying member method code with example usage: obj.tearDownClass(cls) without return types