python编程求解答！

构建一个函数def rightday，判断一个由三个参数构成的日期是否合法！若合法，返回True，否则返回False

import datetime

def rightDay(year,month,day):
    try:
        year , month , day = date_.split()
        print year , month , day
        print datetime.date(int(year) , int(month) , int(day))
        return True 
    except Exception ,e:
        return False