ImmutableSortedSet<Integer> set = ContiguousSet.create(Range.closed(1, 3), integers());
    assertFalse(set.contains(0));
    assertTrue(set.contains(1));
    assertTrue(set.contains(2));
    assertTrue(set.contains(3));
    assertFalse(set.contains(4));
    set = ContiguousSet.create(Range.open(0, 4), integers());
    assertFalse(set.contains(0));
    assertTrue(set.contains(1));
    assertTrue(set.contains(2));

     * @return true if this set contains the specified element.
     */
    @Override
    public boolean contains(final Object o) {
        return map.containsKey(o);
    }

    /**
     * Adds the specified element to this set if it is not already present.
     *
     * @param o
     *            element to be added to this set.

  /**
   * Returns a {@link Set} whose methods throw {@link IllegalStateException} when the given node is
   * not present in this network.
   *
   * @since 33.1.0
   */
  protected final <T> Set<T> nodeInvalidatableSet(Set<T> set, N node) {
    return InvalidatableSet.of(
        set, () -> nodes().contains(node), () -> String.format(NODE_REMOVED_FROM_GRAPH, node));
  }

  /**

    NavigableSet<String> set = create();
    NavigableSet<String> descendingSet = set.descendingSet();
    assertTrue(descendingSet instanceof SynchronizedNavigableSet);
    assertSame(set, ((SynchronizedNavigableSet<String>) descendingSet).mutex);
  }

  public void testHeadSet_E() {
    NavigableSet<String> set = create();
    SortedSet<String> headSet = set.headSet("a");

   * {@link Set}, instead of the {@link Collection} specified in the {@link Multimap} interface.
   */
  @Override
  public Set<Entry<K, V>> entries() {
    return (Set<Entry<K, V>>) super.entries();
  }

  /**
   * {@inheritDoc}
   *
   * <p>Because a {@code SetMultimap} has unique values for a given key, this method returns a

  }

  public void testEmpty_comparator() {
    SortedSet<String> set = of();
    assertSame(Ordering.natural(), set.comparator());
  }

  public void testEmpty_headSet() {
    SortedSet<String> set = of();
    assertSame(set, set.headSet("c"));
  }

  public void testEmpty_tailSet() {
    SortedSet<String> set = of();
    assertSame(set, set.tailSet("f"));
  }

  public void testEmpty_subSet() {

  }

  @Override
  public Set<V> get(@ParametricNullness K key) {
    return (Set<V>) super.get(key);
  }

  @Override
  public Set<V> removeAll(@CheckForNull Object key) {
    return (Set<V>) super.removeAll(key);
  }

  @Override
  public Set<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
    return (Set<V>) super.replaceValues(key, values);
  }

  @Override

func (set TargetIDSet) add(targetID TargetID) {
	set[targetID] = struct{}{}
}

// Union - returns union with given set as new set.
func (set TargetIDSet) Union(sset TargetIDSet) TargetIDSet {
	nset := set.Clone()

	for k := range sset {
		nset.add(k)
	}

	return nset
}

// Difference - returns difference with given set as new set.
func (set TargetIDSet) Difference(sset TargetIDSet) TargetIDSet {

  }

  @Override
  public Set<V> get(@ParametricNullness K key) {
    return (Set<V>) super.get(key);
  }

  @Override
  public Set<V> removeAll(@CheckForNull Object key) {
    return (Set<V>) super.removeAll(key);
  }

  @Override
  public Set<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
    return (Set<V>) super.replaceValues(key, values);
  }

  @Override

                  @Override
                  protected Set<String> create(String[] elements) {
                    Set<String> set = Sets.newHashSet("b", "c");
                    Set<String> other = Sets.newHashSet("a", "b", "c", "d");
                    return Sets.difference(set, other);
                  }
                })
            .named("set - superset")
            .withFeatures(