code: def test_reductions_airline_data(forecaster, expected):
      """Test reduction forecasters.
  
      Test reduction forecasters by making prediction on airline dataset using linear
      estimators. Predictions compared with values calculated by Lovkush Agarwal on their
      local machine in Mar 2021
      """
      y = load_airline()
      y_train, y_test = temporal_train_test_split(y, test_size=24)
      fh = ForecastingHorizon(y_test.index, is_relative=False)
  
      actual = forecaster.fit(y_train, fh=fh).predict(fh)
  
      np.testing.assert_almost_equal(actual, expected)
  
imports: import numpy
  import pandas
  import pytest
  from sklearn.base import BaseEstimator, RegressorMixin
  from sklearn.dummy import DummyRegressor
  from sklearn.linear_model import LinearRegression
  from sklearn.pipeline import make_pipeline
  from sktime.datasets import load_airline
  from sktime.forecasting.base import ForecastingHorizon
  from sktime.forecasting.compose import DirectTabularRegressionForecaster, DirectTimeSeriesRegressionForecaster, DirRecTabularRegressionForecaster, DirRecTimeSeriesRegressionForecaster, MultioutputTabularRegressionForecaster, MultioutputTimeSeriesRegressionForecaster, RecursiveTabularRegressionForecaster, RecursiveTimeSeriesRegressionForecaster, make_reduction
  from sktime.forecasting.compose._reduce import _sliding_window_transform
  from sktime.forecasting.tests._config import TEST_OOS_FHS, TEST_WINDOW_LENGTHS_INT
  from sktime.performance_metrics.forecasting import mean_absolute_percentage_error
  from sktime.regression.base import BaseRegressor
  from sktime.regression.interval_based import TimeSeriesForestRegressor
  from sktime.split import SlidingWindowSplitter, temporal_train_test_split
  from sktime.split.tests.test_split import _get_windows
  from sktime.transformations.panel.reduce import Tabularizer
  from sktime.utils._testing.forecasting import make_forecasting_problem
  from sktime.utils.validation.forecasting import check_fh
label_desc: Use image node_id 14 for calling a global function with example usage: test_reductions_airline_data(forecaster, expected) without return types