def start_game():
    room = 'start'
    while room != 'end':
        if room == 'start':
            print('You are in a dark room. There is a door to the north.')
            choice = input('> ')
            if choice == 'north':
                room = 'treasure'
        elif room == 'treasure':
            print('You found the treasure room! You win!')
            room = 'end'

start_game()