模拟交通十字路口车辆通行规律，设计一个红绿灯控制程序。具体要求如下：用字符画出车道，用字符的不同颜色显示红灯、绿灯、黄灯。根据交通规则控制红绿交替变化，时间自定。在十字路口中间显示倒计时的时间。根据红绿灯状态控制四个方向的车辆移动。-Simulated traffic intersection vehicle traffic laws, to design a traffic light control procedures. Specific requirements are as follows: lane with characters drawn, with characters of different colors red, green, yellow. According to alternate red and green traffic control, time custom. At the crossroads between the time the countdown. State control under the lights of vehicles moving in four directions.