上课编写的一个简单的电梯模拟，可容纳六人，左边控制按钮控制乘客上电梯，右边控制按钮控制乘客下电梯，顶部显示电梯当前运行状态。-class prepared a simple elevator simulation, which can accommodate six people, left control button to control passengers on the elevator, the right control button to control passengers un