code: def assertion_routine(env: ObservationStackWrapper) -> None:
      """Checks if stacking went well."""
      # test application of wrapper
      obs = env.reset()
  
      for _ in range(3):
          observation_keys = list(obs.keys())
          for key in ["observation_0"]:
              assert key in observation_keys
              assert obs[key] in env.observation_spaces_dict[0][key]
          obs = env.step(env.action_space.sample())[0]
  
          observation_keys = list(obs.keys())
          for key in ["observation_1", "observation_1-stacked"]:
              assert key in observation_keys
              assert obs[key] in env.observation_spaces_dict[1][key]
          obs = env.step(env.action_space.sample())[0]
  
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 3 for calling a global function with example usage: assertion_routine(env) without return types