code: def tearDownClass(cls) -> None:
      ray.shutdown()
  
file_path: ray/python/ray/rllib/algorithms/dqn/tests/test_dqn.py
imports: from copy import deepcopy
  import numpy
  import unittest
  import ray
  import ray.rllib.algorithms.dqn
  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 TestDQN obj's underlying member method code with example usage: obj.tearDownClass(cls) without return types