EmptyContiguousSet(DiscreteDomain<C> domain) {
    super(domain);
  }

  @Override
  public C first() {
    throw new NoSuchElementException();
  }

  @Override
  public C last() {
    throw new NoSuchElementException();
  }

  @Override
  public int size() {
    return 0;
  }

  @Override
  public ContiguousSet<C> intersection(ContiguousSet<C> other) {

      }
    }
  }

  @CollectionSize.Require(ZERO)
  public void testEmptySetFirst() {
    assertThrows(NoSuchElementException.class, () -> sortedSet.first());
  }

  @CollectionSize.Require(ZERO)
  public void testEmptySetLast() {
    assertThrows(NoSuchElementException.class, () -> sortedSet.last());
  }

  @CollectionSize.Require(ONE)
  public void testSingletonSetFirst() {

     */
    public E getFirst() {
        if (isEmpty()) {
            throw new NoSuchElementException();
        }
        return getFirstEntry().element;
    }

    /**
     * Returns the last element.
     *
     * @return the last element
     */
    public E getLast() {
        if (isEmpty()) {
            throw new NoSuchElementException();
        }
        return getLastEntry().element;
    }

    /**

          .put(IllegalStateException.class, e -> e instanceof IllegalStateException)
          .put(IndexOutOfBoundsException.class, e -> e instanceof IndexOutOfBoundsException)
          .put(NoSuchElementException.class, e -> e instanceof NoSuchElementException)
          .put(NullPointerException.class, e -> e instanceof NullPointerException)
          .put(NumberFormatException.class, e -> e instanceof NumberFormatException)

          .put(IllegalStateException.class, e -> e instanceof IllegalStateException)
          .put(IndexOutOfBoundsException.class, e -> e instanceof IndexOutOfBoundsException)
          .put(NoSuchElementException.class, e -> e instanceof NoSuchElementException)
          .put(NullPointerException.class, e -> e instanceof NullPointerException)
          .put(NumberFormatException.class, e -> e instanceof NumberFormatException)

          .put(IllegalStateException.class, e -> e instanceof IllegalStateException)
          .put(IndexOutOfBoundsException.class, e -> e instanceof IndexOutOfBoundsException)
          .put(NoSuchElementException.class, e -> e instanceof NoSuchElementException)
          .put(NullPointerException.class, e -> e instanceof NullPointerException)
          .put(NumberFormatException.class, e -> e instanceof NumberFormatException)

          .put(IllegalStateException.class, e -> e instanceof IllegalStateException)
          .put(IndexOutOfBoundsException.class, e -> e instanceof IndexOutOfBoundsException)
          .put(NoSuchElementException.class, e -> e instanceof NoSuchElementException)
          .put(NullPointerException.class, e -> e instanceof NullPointerException)
          .put(NumberFormatException.class, e -> e instanceof NumberFormatException)

          .put(IllegalStateException.class, e -> e instanceof IllegalStateException)
          .put(IndexOutOfBoundsException.class, e -> e instanceof IndexOutOfBoundsException)
          .put(NoSuchElementException.class, e -> e instanceof NoSuchElementException)
          .put(NullPointerException.class, e -> e instanceof NullPointerException)
          .put(NumberFormatException.class, e -> e instanceof NumberFormatException)

          .put(IllegalStateException.class, e -> e instanceof IllegalStateException)
          .put(IndexOutOfBoundsException.class, e -> e instanceof IndexOutOfBoundsException)
          .put(NoSuchElementException.class, e -> e instanceof NoSuchElementException)
          .put(NullPointerException.class, e -> e instanceof NullPointerException)
          .put(NumberFormatException.class, e -> e instanceof NumberFormatException)

          .put(IllegalStateException.class, e -> e instanceof IllegalStateException)
          .put(IndexOutOfBoundsException.class, e -> e instanceof IndexOutOfBoundsException)
          .put(NoSuchElementException.class, e -> e instanceof NoSuchElementException)
          .put(NullPointerException.class, e -> e instanceof NullPointerException)
          .put(NumberFormatException.class, e -> e instanceof NumberFormatException)