classical game: Guess Number for 4A0B !

guess_num.py

import getpass

def guess_num(guess, ans):
    resA, resB = 0, 0

    for index, c in enumerate(guess):
        findAnsRes = ans.find(c)
        if findAnsRes == index:
            resA += 1
        elif findAnsRes >= 0 :
            resB += 1

    return '%dA%dB' % (resA, resB)

def assertions():
    assert guess_num('4567', '1234') == '0A1B'
    assert guess_num('4567', '1567') == '3A0B'
    assert guess_num('4567', '4567') == '4A0B'
    assert guess_num('1234', '5678') == '0A0B'

if __name__ == '__main__':
    assertions()

    res = ''
    answer = getpass.getpass('set up a 4 digit answer!: ')
    print 'guess a 4 digit number!\n'

    while res != '4A0B':
        res = guess_num(str(input('> ')), answer)
        print res

    print 'you win!'