Python在没有datetime库的情况下添加日期

import time

current_time = time.localtime()
year = current_time.tm_year
month = current_time.tm_mon
day = current_time.tm_mday

date = "{}/{}/{}".format(year, month, day)

date_str = "2022-01-01"
year = date_str[:4]
month = date_str[5:7]
day = date_str[8:]

new_date = year + "/" + month + "/" + day