credit card number validator

#### NOTICE ####
# All this code does is VALIDATE the number, checks if its real or not.
# The generator creates a spoof number to test the validator.
# Nothing illegal is happening here

import random
def validate(creditcardnumber):
    # Synopsis:
    # Say you have a number...
    creditcardnumber = [int(i) for i in creditcardnumber]
    for k, v in enumerate(creditcardnumber):
        if k % 2 == 0:
        # Take every other digit from the right
            creditcardnumber[k] = v * 2
            # multiply it by two
    # All added digits are now a sum of digits...
    # that is to say
    # 7 becomes 14, which becomes 1+4, which becomes 5.
    finalstr = ''.join([str(i) for i in creditcardnumber])

    return not sum([int(i) for i in finalstr]) % 10
    # If the sum of all the digits of the final number is a multiple of 10,
    # It's valid!

def generate(cardCpny=None):
    patterns = [
        "4",                                  # 0, Visa
        "5{0}".format(random.randrange(1,6)), # 1, Mastercard
        random.choice(["6011", "644", "65"]), # 2, Discover
        random.choice(["34", "37"])           # 3, American Express
    ]
    foundone = 0
    while not foundone:
        baseStr = [str(random.choice("0123456789")) for i in "_"*16]
        if cardCpny != None:
            for i, digit in enumerate(patterns[cardCpny]):
                baseStr[i] = digit # replace first several digits of base with company digits, if chosen.
        baseStr = ''.join(baseStr)
        if validate(baseStr):
            foundone = 1
            return baseStr

def test():
    thing = {True: "yup.", False: "NOPE!! (This answer will never be printed)"}
    example = generate(2) # discover
    print "Generated #: "+ example
    print "Is it valid? "+ thing[validate(example)]

def main():
    test()

if __name__ == "__main__":
    main()