week by stupid

NOMINAL_WEEK = ('MON', 'TUE', 'WED', 'THU', 'FRI', 'SAT', 'SUN')

def make_shorter(my_days):
    short_record = '' + my_days[0]
    start_week_day = NOMINAL_WEEK.index(my_days[0])
    for i in range(1, len(my_days)):
        if len(my_days) == 1:
            break
        elif i == len(my_days)-1 and my_days[i-1] != NOMINAL_WEEK[NOMINAL_WEEK.index(my_days[i]) - 1]:
            short_record += f',{my_days[i]}'
            break
        elif i == len(my_days)-1 and my_days[i-1] == NOMINAL_WEEK[NOMINAL_WEEK.index(my_days[i]) - 1]:
            short_record += f'-{my_days[i]}'
            break
        elif my_days[i-1] != NOMINAL_WEEK[NOMINAL_WEEK.index(my_days[i]) - 1]:
            short_record += f',{my_days[i]}'
        elif my_days[i+1] != NOMINAL_WEEK[NOMINAL_WEEK.index(my_days[i]) + 1]:
            short_record += f'-{my_days[i]}'
    return short_record

my_days0 = ['SUN']
my_days1 = ['MON', 'TUE', 'WED', 'THU', 'SUN']
my_days2 = ['MON', 'TUE', 'WED', 'THU', 'FRI', 'SAT', 'SUN']
my_days3 = ['MON', 'WED', 'FRI', 'SUN']
my_days4 = ['WED', 'THU', 'FRI', 'SAT', 'SUN']
my_days5 = ['WED', 'THU', 'FRI', 'SUN']
my_days6 = ['MON', 'TUE', 'WED', 'FRI', 'SUN']
my_days7 = ['MON', 'TUE', 'WED', 'FRI', 'SAT', 'SUN']
print(make_shorter(my_days0))
print(make_shorter(my_days1))
print(make_shorter(my_days2))
print(make_shorter(my_days3))
print(make_shorter(my_days4))
print(make_shorter(my_days5))
print(make_shorter(my_days6))
print(make_shorter(my_days7))