python函数 获取两个日期的天数差

import time
st="2021-03-05 00:00:00"
et="2021-03-09 23:59:59"

def tm_array(day1, day2):
    time_array1 = time.strptime(''.join(day1.split(' ')[0]), "%Y-%m-%d")
    timestamp_day1 = int(time.mktime(time_array1))
    time_array2 = time.strptime(''.join(day2.split(' ')[0]), "%Y-%m-%d")
    timestamp_day2 = int(time.mktime(time_array2))
    result = (timestamp_day2 - timestamp_day1) // 60 // 60 // 24
    return result