日付とか

これ便利。

http://labix.org/python-dateutil

>>> from dateutil.relativedelta import *
>>> from datetime import datetime, date, time
>>> now = datetime.now()
>>> now + relativedelta(years=+10)
datetime.datetime(2019, 2, 28, 23, 12, 32, 849974)
>>> now + relativedelta(years=-30, days=-3)
datetime.datetime(1979, 2, 25, 23, 12, 32, 849974)