def rename(index: int) -> Label:
    if multi_index:
        return ('level_{}'.format(index),)
    elif (('index',) not in self._internal.column_labels):
        return ('index',)
    else:
        return ('level_{}'.format(index),)
def rename(index: int) -> Label:
    if multi_index:
        return ('level_{}'.format(index),)
    elif (('index',) not in self._internal.column_labels):
        return ('index',)
    else:
        return ('level_{}'.format(index),)