def ask_ok(prompt, retries=4, complaint='Yes or no, please!'):
    while 1:
        ok = raw_input(prompt)
        if ok in ('y', 'ye', 'yes'): return 1
        if ok in ('n', 'no', 'nop', 'nope'): return 0
        retries = retries - 1
        if retries < 0: raise IOError, 'refusenik user'
        print complaint

quit = 0
while not quit:
   quit = ask_ok(prompt = 'Do you really want to quit?')