python working time snippet

working-time.py

import datetime

def is_working_time(dt = None):
    '''
    is it currently working time?

    tuesday at 8am - yes
    saturday - no
    '''
    #
    # hour ranges e.g. to support lunch break
    work_hours = [(8, 18),] # 8am-6pm
    work_days = list(range(5))
    #
    # dt = datetime.datetime instance
    if dt is None:
        dt = datetime.datetime.now()
    week_day = dt.weekday()
    if not week_day in work_days:
        return False
    hour = dt.hour
    for ranges in work_hours:
        if ranges[0] <= hour < ranges[1]:
            return True
    return False