code: def setUpClass(cls):
      ray.init()
  
file_path: ray/python/ray/rllib/algorithms/impala/tests/test_impala_learner.py
imports: import unittest
  import numpy
  import tree
  import ray
  from ray.rllib.algorithms.impala import ImpalaConfig
  from ray.rllib.policy.sample_batch import SampleBatch
  from ray.rllib.utils.framework import try_import_torch, try_import_tf
  from ray.rllib.utils.test_utils import framework_iterator
  from ray.rllib.utils.torch_utils import convert_to_torch_tensor
label_desc: Use image node_id 1 for calling the TestImpalaLearner obj's underlying member method code with example usage: obj.setUpClass(cls) without return types