code: def test_fit_transform_period_monthly_idx_period_output(
      df_period_monthly_idx,
  ):
      """Tests that we get the expected outputs."""
      transformer = TimeSince(
          start=None,
          to_numeric=False,
          keep_original_columns=False,
          positive_only=False,
      )
  
      transformer.fit(df_period_monthly_idx)
      # Temporary solution to get this test to pass
      # See: https://github.com/sktime/sktime/pull/3810#issuecomment-1320969799
      transformer.set_config(**{"output_conversion": "off"})
      Xt = transformer.transform(df_period_monthly_idx)
      expected = pd.DataFrame(
          data={
              "time_since_2000-01": [
                  i * pd.offsets.MonthEnd() for i in (0, 1, 2, 3, 4)
              ]
          },
          index=df_period_monthly_idx.index,
      )
      assert_frame_equal(Xt, expected)
  
imports: import pandas
  import pytest
  from pandas.testing import assert_frame_equal
  from sktime.transformations.series.time_since import TimeSince
  from sktime.utils._testing.hierarchical import _make_hierarchical
label_desc: Use image node_id 13 for calling a global function with example usage: test_fit_transform_period_monthly_idx_period_output(df_period_monthly_idx) without return types