def get_pk_attrnames(obj) -> List[str]:
    """
    Asks an SQLAlchemy ORM object: "what are your primary key(s)?"

    Args:
        obj: SQLAlchemy ORM object

    Returns:
        list of attribute names of primary-key columns

    """
    return [attrname
            for attrname, column in gen_columns(obj)
            if column.primary_key]