获得昨天和明天的日期

import datetime
import sys

def next_day(date_str):
    date = datetime.datetime.strptime(date_str, '%Y-%m-%d')
    return (date + datetime.timedelta(days=1)).date()

def prev_day(date_str):
    date = datetime.datetime.strptime(date_str,'%Y-%m-%d')
    return (date - datetime.timedelta(days = 1)).date()

while True:
    line = sys.stdin.readline()
    line = line.strip()
    if line == '':
        break
    print('前一天:', prev_day(line))
    print('后一天:', next_day(line))

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2020-04-24