public class Receiver{    public void Action()    {        Console.WriteLine("Action in receiver");    }}
public abstract class Command{    protected readonly Receiver Receiver;
    protected Command(Receiver receiver) =>        Receiver = receiver ?? throw new ArgumentNullException(nameof(receiver));
    public abstract void Execute();}public class ConcreteCommand : Command{    public ConcreteCommand(Receiver receiver) : base(receiver)    {    }
    public override void Execute()    {        Receiver.Action();    }}
public class Invoker{    private Command _command;
    public void SetCommand(Command command)    {        _command = command;    }
    public void ExecuteCommand()    {        _command.Execute();    }}

var receiver = new Receiver();var command = new ConcreteCommand(receiver);var invoker = new Invoker();invoker.SetCommand(command);invoker.ExecuteCommand();
// another samplevar barbecuer = new Barbecuer();var waiter = new Waiter();
waiter.SetOrder(new BakeChickenWingCommand(barbecuer));waiter.SetOrder(new BakeMuttonCommand(barbecuer));waiter.SetOrder(new BakeMuttonCommand(barbecuer));
var willCancelOrder = new BakeMuttonCommand(barbecuer);waiter.SetOrder(willCancelOrder);waiter.CancelOrder(willCancelOrder);
waiter.Notify();