def METHOD_NAME(sum_weekdays_bit: int) -> Set[Days]:
    """Decode a weekdays bit summary to a set of weekdays.
    Args:
        sum_weekdays_bit: the sum of all weekdays
    Return:
        Set of Weekday members decoded from the summary value.
    Todo:
        Should an existing remainder in the sum value throw an error?
        E.g. 3 will result in a set of MONDAY and the remainder will be 1.
    """
    if 1 < sum_weekdays_bit < 255:
        return_weekdays = set()
        weekdays_by_hex = map(lambda w: (w.hex_rep, w), Days)
        for weekday_hex in weekdays_by_hex:
            if weekday_hex[0] & sum_weekdays_bit != 0:
                return_weekdays.add(weekday_hex[1])
        return return_weekdays
    raise ValueError("weekdays bit sum should be between 2 and 254")