<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def attrname_to_colname_dict(cls) -> Dict[str, str]: """ Asks an SQLAlchemy class how its attribute names correspond to database column names. Args: cls: SQLAlchemy ORM class Returns: a dictionary mapping attribute names to database column names """

    attr_col = {}  # type: Dict[str, str]
    for attrname, column in gen_columns(cls):
        attr_col[attrname] = column.name
    return attr_col