信用卡号验证器功能[Python 3]

Question

我是Python编程的初学者，我接受了我在互联网上发现的挑战（信用卡号验证器{Luhn算法}），我写了这个函数：

def CheckNumber(CreditCardNumber) :
    CheckNumberBool = False
    CreditCardNumber = list(map(int, CreditCardNumber))
    x = 1
    y = 0
    WorkingList = list()
    #--------------------------------------------------#
    while x <= 15 :
        WorkingList[x].append(CreditCardNumber[x] * 2)
        x += 2
    #--------------------------------------------------#
    while y <= 15 :
        WorkingList[y].append(CreditCardNumber[y])
        y += 2
    #--------------------------------------------------#
    WorkingListStr = str(sum(WorkingList))
    #--------------------------------------------------#
    while y <= 15 :
        if WorkingList[y] >= 10 :
            for x in WorkingListStr :
                WorkingList.append(int(x))
        y += 1
    #--------------------------------------------------#
    if sum(WorkingList) % 10 == 0 :
        CheckNumberBool = True
        print("This is a Valid Credit Card Number")
    else :
        CheckNumberBool = False
        print("This isn't a Valid Credit Card Number")

但问题是，当我在终端命令行（python3 myfile.py）中运行它时，我收到此错误：

  File "Credit_Card_Algorithm.py", line 13, in CheckNumber
WorkingList[x].append(CreditCardNumber[x] * 2)
IndexError: list index out of range

感谢您提出的所有非常有用的建议，如果我犯了错误，抱歉，这是我第一次写信给巨大的StackOverflow社区;-D