code: def test_observation_stack_wrapper():
      """Observation stacking unit test"""
  
      # instantiate env
      env = build_dummy_structured_environment()
  
      # wrapper config
      config = {
          "stack_config": [
              {
                  "observation": "observation_0",
                  "keep_original": False,
                  "tag": None,
                  "delta": True,
                  "stack_steps": 2,
              },
              {
                  "observation": "observation_1",
                  "keep_original": True,
                  "tag": "stacked",
                  "delta": False,
                  "stack_steps": 2,
              },
          ]
      }
  
      env = ObservationStackWrapper.wrap(
          env, stack_config=config["stack_config"]
      )
  
      # test application of wrapper
      assertion_routine(env)
  
file_path: maze/maze/test/core/wrappers/test_observation_stack_wrapper.py
imports: from copy import deepcopy
  import maze.test.core.wrappers
  from maze.core.wrappers.observation_stack_wrapper import ObservationStackWrapper
  from maze.test.shared_test_utils.config_testing_utils import load_env_config
  from maze.test.shared_test_utils.dummy_env.dummy_core_env import DummyCoreEnvironment
  from maze.test.shared_test_utils.dummy_env.dummy_maze_env import DummyEnvironment
  from maze.test.shared_test_utils.dummy_env.dummy_struct_env import DummyStructuredEnvironment
  from maze.test.shared_test_utils.dummy_env.space_interfaces.action_conversion.dict_discrete import DictDiscreteActionConversion
  from maze.test.shared_test_utils.dummy_env.space_interfaces.observation_conversion.dict import ObservationConversion
label_desc: Use image node_id 4 for calling a global function with example usage: test_observation_stack_wrapper() without return types