class_docstr: Sanity tests for A2C exec impl.
code: def tearDown(self):
      ray.shutdown()
  
file_path: ray/rllib_contrib/a3c/tests/test_a3c.py
imports: import unittest
  from rllib_a3c.a3c import A3CConfig
  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_compute_single_action, check_train_results, framework_iterator
label_desc: Use image node_id 2 for calling the TestA3C obj's underlying member method code with example usage: obj.tearDown() without return types