构建函数，判断一个日期是否合法！

构建一个函数，判断一个由三个参数构成的日期是否为合法日期，合法，返回True，否则返回False.

def fn3(year, month, day):
    if month > 12 or month <= 0:
        return "%s年%s月%s日不是合法日期"%(year,month,day)
    if num_6(year):
        months = [31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
        if day <= months[month-1]:
            return "合法日期"
        else:
            return "%s年%s月%s日不是合法日期" % (year, month, day)
    else:
        month2 = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
        if day <= month2[month - 1]:
             return "合法日期"
        else:
            return "%s年%s月%s日不是合法日期" % (year, month, day)
 
# print(fn3(2020, 1, 31))


def youhua(year, month, day):
    if month < 1 or month >12:
        return False
    days = 31
    if month in [4,6,9,11]:
        days = 30
    elif month == 2:
        if num_6(year):
            days = 29
        else:
            days = 28
    if day < 1 and day>days:
        return False
    return True
 
# print(youhua(2020, 1, 31))<br><br>