Command design pattern. Simple version.

Hello
We have Light devices, which can beam or not.
We do not want control directly Light source, because we want learn Command Design Pattern :-)
Of course, the reasons is others. For example, we want to be less sensitive to changes.

In implementation of Command Design Patter in our example we have 3 players:

• Device: is a Light which can be "ON" or "OFF" state.
• Command turn "ON" the lights: is Light "ON" command. Is a class, which wraps above Light. Heart of this class - turn "ON" the Light, which encapsulated in single function "Execute". 
• Remote: some class which got command and call it "Execute". When user call "Click Remote" of this class, its method call "Execute" of command

Illustration:

Code behind it:

public interface ICommand
{
    void Execute();
}

public class Light
{
    public void On()
    {
        Console.WriteLine("Light is ON");
    }

    public void Off()
    {
        Console.WriteLine("Light is OFF");
    }
}

public class LightOnCommand : ICommand
{
    private Light _light;

    public LightOnCommand(Light light)
    {
        _light = light;
    }

    public void Execute()
    {
        _light.On();
    }
}

public class SimpleRemoteControl
{
    ICommand _command;

    public void SetCommand(ICommand command)
    {
        _command = command;
    }

    public void ClickButton()
    {
        _command.Execute();
    }
}

Tester:

Light light = new Light();
ICommand lightOnCmd = new LightOnCommand(light);

SimpleRemoteControl remote = new SimpleRemoteControl();
remote.SetCommand(lightOnCmd);
remote.ClickButton();

Result: