in spotify_confidence/analysis/bayesian/bayesian_base.py [0:0]
def _add_level_column(self, groupby, level_as_reference):
level_column = "level_2" if level_as_reference else "level_1"
if groupby is None:
groupby_columns = level_column
else:
if isinstance(groupby, str):
groupby_columns = [groupby, level_column]
else:
groupby_columns = groupby + [level_column]
return groupby_columns