实现八个流水灯的功能，首先先从左到右，每次只亮一个发光二极光，然后再从右到左，往复循环。LED灯的亮、熄间隔扎500ms，延时时间不大于5 。-Realize the function of eight of flowing water light, first from left to right, each only light a led two lights, and then from right to left, reciprocating cycle. LED lamp light, plunge 500 ms out interval, delay time to no more than 5 .