from sys import exit
def playAgain():
print('Do you want to play again? (yes or no)')
while True:
    if input("> ").lower().startswith('yes')== True:
        start()
    elif input("> ").lower().startswith('no')== True:
        print ('Bye for now')
        exit(0)
    else:
        print ("I don't understand what you mean?")