def bonus(settings, screen, stats, snake_head, snake_parts, foods):
# 加分
stats.score += settings.bonus_points * stats.level
# 清空食物，并增加bonus样式的食物
foods.empty()
while len(foods) < settings.bonus_food:
food = Food(screen, settings)
food.random_pos(snake_head, snake_parts, foods)
food.bonus_mode()
foods.add(food)
# 将蛇长度缩短
if stats.snake_length > settings.bonus_cut_length:
stats.snake_length -= settings.bonus_cut_length
else:
stats.snake_length = 1
for part in snake_parts.copy():
if not part.check_alive(stats.snake_length):
snake_parts.remove(part)
