using System.Collections.Generic;namespace DesignPattern.Structural.Composite{    public abstract class Component    {        public virtual void Show(int level) { }        public abstract void Add(Component component);        public abstract void Remove(Component component);    }    public class Composite : Component    {        public List<Component> Components { get; set; }        public override void Add(Component component)        {            Components.Add(component);        }        public override void Remove(Component component)        {            Components.Remove(component);        }        public override void Show(int level)        {            base.Show(level);            foreach (var component in Components)            {                component.Show(level + 1);            }        }    }    public class Leaf : Component    {        public override void Add(Component component)        {            throw new System.NotImplementedException();        }        public override void Remove(Component component)        {            throw new System.NotImplementedException();        }    }}