python 怎么根据当前日期获取上上周，周日的日期

python 怎么根据当前日期获取上上周，周日的日期
比如当前日期是2021-09-29，想要得到上上周 周期的日期，就是2020-09-19的日期

import datetime
day_Week = datetime.datetime.now().isoweekday()
nowtime = datetime.datetime.now()
delta = datetime.timedelta(days=7 + day_Week)
n_days = nowtime - delta
print(n_days.strftime('%Y-%m-%d %H:%M:%S'))

from dateutil.relativedelta import relativedelta
from datetime import datetime
now=datetime(2021,9,29)
last_lastweek=(now-relativedelta(days=(now.weekday()+1))-relativedelta(weeks=1)).strftime('%Y-%m-%d')
print(last_lastweek)

如果帮到你，帮忙采纳下，多谢！