python 程序计时

from time import sleep
from datetime import datetime

date_time_format = '%y-%M-%d %H:%M:%S'
def date_time_str(date_time):
    return datetime.strftime(date_time, date_time_format)

def loop_one():
    print(f'+++线程一开始于:{date_time_str(datetime.now())}')
    print('+++线程一休眠4秒')
    sleep(4)
    print(f'+++线程一休眠结束，结束于:{date_time_str(datetime.now())}')