Zeller在Python中的一致性，,年问题

Question

我是Python和编程的新手。而且我正在与Zeller的全能一起练习，遇到一天中的问题。我遇到的问题是我似乎无法将/年与其他代码连接/实现。请帮忙。

    year = int(input("Year: "))
    while year < 1583 or year > 9999:
        print("Out of allowed range 1583 - 9999 ")
        year = int(input("Year: "))

    def leapYear(year):
        if year %400 == 0 :
            return True
        elif year %100 == 0 :
            return False
        elif year % 4 == 0 :
            return True
        elif year %4 != 0 :
            return False

    month = int(input("Month: "))
    while month < 1 or month > 12:
        print("Out of allowed range 1 – 12 ")
        month = int(input("Month: "))

    def validDay(year,month,day):
        # Months 4, 6, 9, 11 have 30 days
        if month == 4 and day >= 31 or 6 and day >= 31 or 9 and day >= 31 or 11 and day >= 31 :
            return False
        # Month 2 has 28 days, except during a leap year, when it has 29.
        elif month == 2 and day < 30 and leapYear is True :
            return True
        elif month ==2 and day > 28 and leapYear is False:
            return False
        elif month ==2 and day <= 28:
            return True
        # Rest have 31 days.
        elif day > 31:
            print("Out of allowed range 1 - 31 ")
            day = int(input("Day: "))
        elif day < 32:
            return True

    if month == 1 or month == 2:
     month += 12
     year -= 1 

    day = int(input("Day: "))
    while day < 1 or day > 31 :
        print("Out of allowed range 1 - 31 ")
        day = int(input("Day: "))

    if month == 1:
        month = month + 12
        year = year - 1
    elif month == 2:
        month = month + 12
        year = year - 1

    century = (year // 100)
    century_year = (year % 100)

    weekday = (day + ((26 * (month + 1)) // (10)) + century_year + ((century_year) // \
        (4)) + ((century) // (4)) + (5 * century)) % 7

    if weekday == 0:
        print('It is Saturday')
    elif weekday == 1:
        print('It is Sunday')
    elif weekday == 2:
        print('It is Monday')
    elif weekday == 3:
        print('It is Tuesday')
    elif weekday == 4:
        print('It is Wednesday')
    elif weekday == 5:
        print('It is Thursday')
    elif weekday == 6:
        print('It is Friday')

我如何理解/连接年输入和月输入以及最后输入一天？