code: def tearDown(self):
      ray.shutdown()
      _register_all()
  
imports: import os
  import numpy
  import random
  import unittest
  import ray
  from ray.rllib import _register_all
  from ray import tune
  from ray.tune.result import DEFAULT_RESULTS_DIR
  from ray.tune.search import grid_search, BasicVariantGenerator
  from ray.tune.search.variant_generator import RecursiveDependencyError, _resolve_nested_dict
label_desc: Use image node_id 2 for calling the VariantGeneratorTest obj's underlying member method code with example usage: obj.tearDown() without return types