code: def test_lag_fit_transform_out_values(X, index_out, remember_data):
      """Test that index sets of fit_transform output behave as expected."""
      t = Lag(2, index_out=index_out, remember_data=remember_data)
      if isinstance(X, pd.Series):
          X = pd.DataFrame(X)
      X_fit = X[:2]
      X_trafo = X[2:]
      Xt = t.fit(X_fit).transform(X_trafo)
  
      if index_out in ["original", "extend"]:
          if remember_data:
              np.testing.assert_equal(
                  Xt.iloc[0].values, X_fit.iloc[0].values
              )
          else:  # remember_data == False
              assert all(Xt.iloc[0].isna().values)
          if len(Xt) > 2:
              np.testing.assert_equal(
                  Xt.iloc[2].values, X_trafo.iloc[0].values
              )
  
      elif index_out == "shift":
          np.testing.assert_equal(Xt.values, X_trafo.values)
  
file_path: sktime/sktime/transformations/series/tests/test_lag.py
imports: import itertools
  import numpy
  import pandas
  import pytest
  from sktime.datatypes import get_examples
  from sktime.transformations.series.lag import Lag
  from sktime.utils._testing.series import _make_series
label_desc: Use image node_id 2 for calling a global function with example usage: test_lag_fit_transform_out_values(X, index_out, remember_data) without return types