code: def test_return_pandas_series_when_input_pandas_and_len_periods_one(
      data_pd,
  ):
      mod = MSTL(endog=data_pd, periods=5)
      res = mod.fit()
      assert isinstance(res.trend, pd.Series)
      assert isinstance(res.seasonal, pd.Series)
      assert isinstance(res.resid, pd.Series)
      assert isinstance(res.weights, pd.Series)
  
file_path: statsmodels/statsmodels/tsa/stl/tests/test_mstl.py
imports: from pathlib import Path
  from numpy.testing import assert_allclose, assert_equal
  import pandas
  import pytest
  from statsmodels.tsa.seasonal import MSTL
label_desc: Use image node_id 4 for calling a global function with example usage: test_return_pandas_series_when_input_pandas_and_len_periods_one(data_pd) without return types