namespace DesignPattern.Creational.Builder{    public class Director    {        private Builder _builder;        public void SetBuilder(Builder builder)        {            _builder = builder;        }        public void Show()        {            _builder.ShowA();            _builder.ShowB();        }    }    public abstract class Builder    {        public abstract void ShowA();        public abstract void ShowB();    }    public class BuilderA : Builder    {        public override void ShowA() { }        public override void ShowB() { }    }    public class BuilderB : Builder    {        public override void ShowA() { }        public override void ShowB() { }    }}