code: def test_vectorize_reconstruct_unique_columns():
      """Tests that vectorization on multivariate output yields unique columns.
  
      Also test that the column names are as expected:
      <variable>__<transformed> if multiple transformed variables per variable are present
      <variable> if one variable is transformed to one output
  
      Raises
      ------
      AssertionError if output columns are not as expected.
      """
      from sktime.transformations.series.detrend import Detrender
      from sktime.transformations.series.theta import (
          ThetaLinesTransformer,
      )
  
      X = pd.DataFrame({"a": [1, 2], "b": [3, 4], "c": [5, 6]})
      X_mi = get_examples("pd_multiindex_hier")[0]
  
      t = ThetaLinesTransformer()
  
      X_t_cols = t.fit_transform(X).columns
  
      assert set(X_t_cols) == {
          "a__0",
          "a__2",
          "b__0",
          "b__2",
          "c__0",
          "c__2",
      }
  
      X_mi_cols = t.fit_transform(X_mi)
      assert set(X_mi_cols) == {
          "var_0__0",
          "var_0__2",
          "var_1__0",
          "var_1__2",
      }
  
      X = _make_series(n_columns=2, n_timepoints=15)
      t = Detrender.create_test_instance()
      Xt = t.fit_transform(X)
      assert set(Xt.columns) == {0, 1}
  
imports: from inspect import isclass
  import pandas
  import pytest
  from sktime.datatypes import check_is_scitype, get_examples, mtype_to_scitype
  from sktime.transformations.compose import FitInTransform
  from sktime.transformations.panel.padder import PaddingTransformer
  from sktime.transformations.panel.tsfresh import TSFreshFeatureExtractor, TSFreshRelevantFeatureExtractor
  from sktime.transformations.series.boxcox import BoxCoxTransformer
  from sktime.transformations.series.exponent import ExponentTransformer
  from sktime.transformations.series.summarize import SummaryTransformer
  from sktime.utils._testing.scenarios_transformers import TransformerFitTransformHierarchicalMultivariate, TransformerFitTransformHierarchicalUnivariate, TransformerFitTransformPanelUnivariate, TransformerFitTransformPanelUnivariateWithClassYOnlyFit, TransformerFitTransformSeriesMultivariate, TransformerFitTransformSeriesUnivariate
  from sktime.utils._testing.series import _make_series
  from sktime.utils.parallel import _get_parallel_test_fixtures
  from sktime.utils.validation._dependencies import _check_soft_dependencies
label_desc: Use image node_id 17 for calling a global function with example usage: test_vectorize_reconstruct_unique_columns() without return types