code: def _check_columns(z, selected_columns):
      # make sure z contains all columns that the user wants to transform
      z_wanted_keys = set(selected_columns)
      z_new_keys = set(z.columns)
      difference = z_wanted_keys.difference(z_new_keys)
      if len(difference) != 0:
          raise ValueError(
              "Missing columns" + str(difference) + "in Z."
          )
  
imports: import pandas
  from sktime.base._meta import _ColumnEstimator, _HeterogenousMetaEstimator
  from sktime.transformations.base import BaseTransformer
  from sktime.utils.multiindex import rename_multiindex
  from sktime.utils.validation.series import check_series
label_desc: Use image node_id 1 for calling a global function with example usage: _check_columns(z, selected_columns) without return types