enum FlippableMember {
	A(Flippable.A), B(Flippable.B), Y(Flippable.Y), Z(Flippable.Z);
	private final Flippable value;

  private FlippableMember(Flippable value) {
    this.value = value;
  }

  public Flippable value() {
    return value;
  }
}

enum Flippable {
  A (FlippableMember.Z), B (FlippableMember.Y), Y (FlippableMember.B), Z (FlippableMember.A);

  private final Flippable opposite;

  private Flippable(FlippableMember opposite) {
    this.opposite = opposite.value();
  }

  public Flippable flip() {

package test;

public class Flippable {
	private static final A a = new A(z);
	private static final B b = new B(y);
	private static final Y y = new Y(b);
	private static final Z z = new Z(a);

	public static class A extends Flippable {
		public A(Flippable opposite) {
			super(opposite);
		}
	}

	public static class B extends Flippable {
		public B(Flippable opposite) {
			super(opposite);
		}
	}

	public static class Y extends Flippable {
		public Y(Flippable opposite) {
			super(opposite);
		}

brain.Clone()

        /// <summary>
        /// Extracts the value attribute from the HTML element having the specified id attribute.
        /// </summary>
        public string Extract(string id)
        {
            return Regex.Match(Html, @"id=""" + id + @""" value=""([^""]*)")
                        .Groups[1]
                        .Value;
        }