code: def test_get_fitted_params_sklearn_nested():
      """Tests fitted parameter retrieval with sklearn components.
  
      Raises
      ------
      AssertionError if logic behind get_fitted_params is incorrect, logic tested:
          calling get_fitted_params on obj sktime component returns expected nested params
      """
      from sklearn.linear_model import LinearRegression
      from sklearn.pipeline import make_pipeline
      from sklearn.preprocessing import StandardScaler
  
      from sktime.datasets import load_airline
      from sktime.forecasting.trend import TrendForecaster
  
      y = load_airline()
      pipe = make_pipeline(StandardScaler(), LinearRegression())
      f = TrendForecaster(pipe)
      f.fit(y)
  
      params = f.get_fitted_params()
  
      assert "regressor" in params.keys()
      assert "regressor__n_features_in" in params.keys()
  
label_desc: Use image node_id 2 for calling a global function with example usage: test_get_fitted_params_sklearn_nested() without return types