@staticmethod
def to_role(column_name, suffix='_column_name'):
    """
        Converts an attribute name to role
        ``row_group_column_name -> group_id``.
        """
    if not isinstance(column_name, str):
        raise TypeError("Unexpected column_name '{0}'".format(column_name))
    if column_name == 'example_weight' + suffix:
        return 'weight'
    if column_name == 'row_group' + suffix:
        return 'group_id'
    return column_name.lower().split(suffix)[0]
