code: def test_pre_processing_wrapper():
      """Pre-processor unit test"""
  
      # instantiate env
      env = build_dummy_structured_environment()
  
      # pre-processor config
      config = {
          "pre_processor_mapping": [
              {
                  "observation": "observation_0_feature_series",
                  "_target_": "maze.preprocessors.FlattenPreProcessor",
                  "keep_original": True,
                  "config": {"num_flatten_dims": 2},
              },
              {
                  "observation": "observation_1_categorical_feature",
                  "_target_": "maze.preprocessors.OneHotPreProcessor",
                  "keep_original": False,
                  "config": {},
              },
          ]
      }
  
      env = PreProcessingWrapper.wrap(
          env, pre_processor_mapping=config["pre_processor_mapping"]
      )
  
      # test application of wrapper
      obs = env.reset()
      observation_keys = list(obs.keys())
  
      assert "observation_1_categorical_feature" not in observation_keys
      assert (
          "observation_1_categorical_feature-one_hot"
          not in observation_keys
      )
  
      for key in [
          "observation_0_feature_series",
          "observation_0_feature_series-flatten",
      ]:
          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())
  
      assert "observation_0_feature_series" not in observation_keys
      assert (
          "observation_0_feature_series-flatten" not in observation_keys
      )
      assert "observation_1_categorical_feature" not in observation_keys
  
      for key in ["observation_1_categorical_feature-one_hot"]:
          assert key in observation_keys
          assert obs[key] in env.observation_spaces_dict[1][key]
  
imports: import maze.test.core.wrappers.observation_preprocessing
  from maze.core.wrappers.observation_preprocessing.preprocessing_wrapper import PreProcessingWrapper
  from maze.test.core.wrappers.observation_preprocessing.preprocessor_testing_utils import build_dummy_structured_environment
  from maze.test.shared_test_utils.config_testing_utils import load_env_config
label_desc: Use image node_id 1 for calling a global function with example usage: test_pre_processing_wrapper() without return types