时间日期加减

比如今天是2023-09-01，想要2023-08-01，也就是减去 一个月，Python中大概是

today = datetime.date(2023, 9, 1)

first = today.replace(day=1)

last = today.replace(day=1) - datetime.timedelta(days=1)

previous_month_day = last.replace(day=today.day)但是影刀 中这样是错的，请问影刀中时间日期减去一个月怎么减呀？