led

代码说明：

  控制8个发光二极管中的一个发光二极管发光，其它7个发光二极管都出于截止状态，发光二极管的导通顺序按照向左或向右两个方向移动，并且通过按键控制发光二极管循环发光移动的方向。(Control of a light-emitting diode light-emitting eight light-emitting diodes, the other seven light-emitting diodes for the cut-off state, light-emitting diode conduction order in accordance with the left or right move in both directions, and light-emitting diode cycle luminous button control mobile direction.)