import datetime
def last_day_of_month(any_day):
# get close to the end of the month for any day, and add 4 days 'over'
next_month = any_day.replace(day=28) + datetime.timedelta(days=4)
# subtract the number of remaining 'overage' days to get last day of current month, or said programattically said, the previous day of the first of next month
return next_month - datetime.timedelta(days=next_month.day)
last_date_of_month(datetime.date.today())