python 日期运算

import datetime

timeNow = datetime.datetime.now()
# 当前日期
today = timeNow.strftime('%Y%m%d%H%M%S')
# 昨天
yesterday = (timeNow - datetime.timedelta(days=1)).strftime('%Y%m%d%H%M%S')
# 二十天前
twentyDaysAgo = (timeNow - datetime.timedelta(days=20)).strftime('%Y%m%d%H%M%S')