python 时间库的用法

1. 月份的加减

　　https://blog.csdn.net/qq_18863573/article/details/79444094

　　第三方模块：python-dateutil

import datetime  
from dateutil.relativedelta import relativedelta  
  
datetime_now = datetime.datetime.now()  
datetime_three_month_ago = datetime_now - relativedelta(months=3)  
print datetime_three_month_ago