using System.Collections.Generic;namespace DesignPattern.Behavioral.Command{    public class Receiver    {        public void ShowA() { }        public void ShowB() { }    }    public class Invoker    {        public List<Command> Commands { get; set; }        public void Add(Command command) { Commands.Add(command); }        public void Remove(Command command) { Commands.Remove(command); }        public void Notify()        {            foreach (var command in Commands)            {                command.Show();            }        }    }    public abstract class Command    {        protected Receiver Receiver = new Receiver();        public abstract void Show();    }    public class CommandA : Command    {        public override void Show()        {            Receiver.ShowA();        }    }    public class CommandB : Command    {        public override void Show()        {            Receiver.ShowB();        }    }}