def __init__(self, first, last=None):
        try:
            first_num = WEEKDAYS.index(first.lower())
        except __HOLE__:
            raise ValueError('Invalid weekday name "%s"' % first)

        if last:
            try:
                last_num = WEEKDAYS.index(last.lower())
            except ValueError:
                raise ValueError('Invalid weekday name "%s"' % last)
        else:
            last_num = None

        RangeExpression.__init__(self, first_num, last_num)
dataset/ETHPy150Open agronholm/apscheduler/apscheduler/triggers/cron/expressions.py/WeekdayRangeExpression.__init__