*/
  public static DiscreteDomain<Integer> integers() {
    return IntegerDomain.INSTANCE;
  }

  private static final class IntegerDomain extends DiscreteDomain<Integer> implements Serializable {
    private static final IntegerDomain INSTANCE = new IntegerDomain();

    IntegerDomain() {
      super(true);
    }

    @Override
    public @Nullable Integer next(Integer value) {