code: def test_exponential_smoothing():
      """Test failure case from #1876.
  
      https://github.com/sktime/sktime/issues/1876#issue-1103752402.
      """
      y = load_airline()
      # Change index to 10 min interval
      freq = "10Min"
      time_range = pd.date_range(
          pd.to_datetime("2019-01-01 00:00"),
          pd.to_datetime("2019-01-01 23:55"),
          freq=freq,
      )
      # Period Index does not work
      y.index = time_range.to_period()
  
      forecaster = ExponentialSmoothing(
          trend="add", seasonal="multiplicative", sp=12
      )
      forecaster.fit(y, fh=[1, 2, 3, 4, 5, 6])
      y_pred = forecaster.predict()
      pd.testing.assert_index_equal(
          y_pred.index,
          pd.period_range("2019-01-02 00:00", periods=6, freq=freq),
      )
  
imports: from datetime import timedelta
  import numpy
  import pandas
  import pytest
  from numpy.testing._private.utils import assert_array_equal
  from pytest import raises
  from sktime.datasets import load_airline
  from sktime.datatypes._utilities import get_cutoff
  from sktime.forecasting.arima import AutoARIMA
  from sktime.forecasting.base import ForecastingHorizon
  from sktime.forecasting.base._fh import DELEGATED_METHODS, _check_freq, _extract_freq_from_cutoff
  from sktime.forecasting.ets import AutoETS
  from sktime.forecasting.exp_smoothing import ExponentialSmoothing
  from sktime.forecasting.naive import NaiveForecaster
  from sktime.forecasting.tests._config import INDEX_TYPE_LOOKUP, TEST_FHS, TEST_FHS_TIMEDELTA, VALID_INDEX_FH_COMBINATIONS
  from sktime.split import temporal_train_test_split
  from sktime.tests.test_switch import run_test_for_class
  from sktime.utils._testing.forecasting import _make_fh, make_forecasting_problem
  from sktime.utils._testing.series import _make_index, _make_series
  from sktime.utils.datetime import _coerce_duration_to_int, _get_duration, _get_freq, _get_intervals_count_and_unit, _shift, infer_freq
  from sktime.utils.validation.series import is_in_valid_index_types, is_integer_index
label_desc: Use image node_id 26 for calling a global function with example usage: test_exponential_smoothing() without return types