code: def test_column_ensemble_hierarchical():
      """Tests column ensemble with hierarchical reconciliation, see bug #3784."""
      from sktime.datatypes import get_examples
      from sktime.datatypes._utilities import get_window
      from sktime.forecasting.sarimax import SARIMAX
      from sktime.transformations.hierarchical.aggregate import (
          Aggregator,
      )
      from sktime.transformations.hierarchical.reconcile import (
          Reconciler,
      )
  
      X = get_examples("pd_multiindex_hier")[0]
      y = get_examples("pd_multiindex_hier")[1]
  
      X_train = get_window(X, lag=1)
      y_train = get_window(y, lag=1)
  
      f = Aggregator() * (Aggregator() ** SARIMAX()) * Reconciler()
  
      f_hat = ColumnEnsembleForecaster(f)
      f_hat.fit(y=y_train, X=X_train, fh=1)
  
file_path: sktime/sktime/forecasting/compose/tests/test_column_ensemble.py
imports: import numpy
  import pandas
  import pytest
  from sktime.forecasting.compose import ColumnEnsembleForecaster
  from sktime.forecasting.naive import NaiveForecaster
  from sktime.forecasting.trend import PolynomialTrendForecaster
  from sktime.utils.validation._dependencies import _check_soft_dependencies
label_desc: Use image node_id 5 for calling a global function with example usage: test_column_ensemble_hierarchical() without return types