pip install python-dateutil

import datetime
print datetime.datetime.now()
# 2018-05-08 16:53:30.101000

import datetime
print datetime.datetime.now().strftime("%Y-%m-%d %H:%M")
# 2018-05-08 16:54

import datetime
print (datetime.datetime.now()+datetime.timedelta(days=1)).strftime("%Y-%m-%d %H:%M:%S")
# 2018-05-09 16:56:07

import datetime
print (datetime.datetime.now()+datetime.timedelta(days=-1)).strftime("%Y-%m-%d %H:%M:%S")
# 2018-05-07 16:56:59

timedelta([days[, seconds[, microseconds[, milliseconds[, minutes[,
hours[, weeks]]]]]]])

import datetime
from dateutil.relativedelta import relativedelta
d = datetime.datetime.strptime('20180131', '%Y%m%d')
print(d) // 2018-01-31 00:00:00
print((d - relativedelta(years=1)).strftime('%Y%m%d')) // 20170131

> print (datetime.datetime.now()+datetime.timedelta(minutes=1)).strftime("%Y-%
m-%d %H:%M:%S")
2017-07-15 15:12:56
>