python判斷當月有多少天

def get_last_day(year, month):
    # 判斷是否爲閏年，當flag爲True時，表示是閏年
    flag = False
    if year%4 == 0 and year%100 != 0:
        flag = True
    if year%400 == 0:
        flag = True
    if month in [1,3,5,7,8,10,12]:
        return 31
    if month in [4,6,9,11]:
        return 30
    if month == 2 and flag == True:
        return 29
    if month == 2 and flag == False:
        return 28

以後說不定用得上