class_docstr: Tests some sanity checks that should pass based on the math of ope methods.
code: def tearDownClass(cls):
      ray.shutdown()
  
imports: import unittest
  import time
  import gymnasium
  import torch
  import numpy
  from ray.rllib.offline.estimators import DirectMethod, DoublyRobust, ImportanceSampling, WeightedImportanceSampling
  from ray.rllib.models.torch.torch_action_dist import TorchCategorical
  from ray.rllib.policy.sample_batch import SampleBatch
  from ray.rllib.policy.torch_policy_v2 import TorchPolicyV2
  from ray.rllib.utils.test_utils import check
  import ray
label_desc: Use image node_id 2 for calling the TestOPEMath obj's underlying member method code with example usage: obj.tearDownClass(cls) without return types