写一个简单函数，使Add a method called “switchLight” which turns the light on if it is off, and vice versa

当然，我们可以创建一个简单的 `Light` 类，包含一个私有布尔变量 `isOn` 来表示灯的状态，然后定义一个名为 `switchLight` 的公共方法来切换灯。这里是一个Java示例：

public class Light {
    private boolean isOn;

    public Light() {
        this.isOn = false; // 默认灯关闭
    }

    // Getter and Setter for isOn property
    public boolean getIsOn() {
        return isOn;
    }

    public void setIsOn(boolean isOn) {
        this.isOn = isOn;
    }

    /**
     * Method to switch the light on or off based on its current state.
     */
    public void switchLight() {
        if (isOn) {
            System.out.println("Turning off the light.");
            isOn = false;
        } else {
            System.out.println("Turning on the light.");
            isOn = true;
        }
    }
}

// Usage example
public class Main {
    public static void main(String[] args) {
        Light light = new Light();
        light.switchLight(); // Initially, prints "Turning on the light."
        light.switchLight(); // After first call, prints "Turning off the light."
    }
}

这个 `switchLight` 方法检查当前灯是否打开，如果打开则关闭，反之则打开。你可以根据需要扩展这个类或添加更多的功能。