code: def test_seasonal_periods(austourists):
      # test auto-deduction of period
      model = ETSModel(
          austourists, error="add", trend="add", seasonal="add"
      )
      assert model.seasonal_periods == 4
  
      # test if seasonal period raises error
      try:
          model = ETSModel(
              austourists, seasonal="add", seasonal_periods=0
          )
      except ValueError:
          pass
  
imports: from statsmodels.compat.pandas import QUARTER_END
  from statsmodels.compat.platform import PLATFORM_LINUX32, PLATFORM_WIN
  from itertools import product
  import json
  import pathlib
  import numpy
  from numpy.testing import assert_allclose, assert_almost_equal
  import pandas
  import pytest
  import scipy.stats
  from statsmodels.tsa.exponential_smoothing.ets import ETSModel
  import statsmodels.tsa.holtwinters
  import statsmodels.tsa.statespace.exponential_smoothing
label_desc: Use image node_id 26 for calling a global function with example usage: test_seasonal_periods(austourists) without return types