code: def test_normalization_strategies():
      """normalization strategy test"""
  
      for normalization_strategy_cls in [
          MeanZeroStdOneObservationNormalizationStrategy,
          RangeZeroOneObservationNormalizationStrategy,
      ]:
          structured_space = get_structured_space()
  
          observation_space = structured_space[0]["box"]
          normalization_strategy = normalization_strategy_cls(
              observation_space, clip_range=(0, 1), axis=0
          )
          assert isinstance(
              normalization_strategy, normalization_strategy_cls
          )
          assert normalization_strategy.is_initialized() is False
  
          observations = [
              observation_space.sample() for _ in range(100)
          ]
          stats = normalization_strategy.estimate_stats(observations)
          normalization_strategy.set_statistics(stats)
          assert normalization_strategy.is_initialized() is True
          for (
              key,
              value,
          ) in normalization_strategy.get_statistics().items():
              assert np.all(stats[key] == value)
  
          normalized_observation_space = (
              normalization_strategy.normalized_space()
          )
          assert np.all(normalized_observation_space.low >= 0)
          assert np.all(normalized_observation_space.high <= 1)
  
          normalized_observation = (
              normalization_strategy.normalize_and_process_value(
                  observations[0]
              )
          )
          assert normalized_observation in normalized_observation
  
imports: import gym
  import numpy
  from maze.core.wrappers.observation_normalization.normalization_strategies.mean_zero_std_one import MeanZeroStdOneObservationNormalizationStrategy
  from maze.core.wrappers.observation_normalization.normalization_strategies.range_zero_one import RangeZeroOneObservationNormalizationStrategy
label_desc: Use image node_id 2 for calling a global function with example usage: test_normalization_strategies() without return types