@GwtIncompatible
public final class SafeTreeSet<E> implements Serializable, NavigableSet<E> {
  @SuppressWarnings("unchecked")
  private static final Comparator<Object> NATURAL_ORDER =
      new Comparator<Object>() {
        @Override
        public int compare(Object o1, Object o2) {
          return ((Comparable<Object>) o1).compareTo(o2);
        }
      };

  private final NavigableSet<E> delegate;

  public SafeTreeSet() {

    return tailMap(fromKey, true);
  }

  @Override
  public NavigableSet<K> navigableKeySet() {
    return new Maps.NavigableKeySet<>(this);
  }

  @Override
  public Set<K> keySet() {
    return navigableKeySet();
  }

  @Override
  public NavigableSet<K> descendingKeySet() {
    return descendingMap().navigableKeySet();
  }

  @Override

  }

  @GwtIncompatible // NavigableSet
  static <E extends @Nullable Object> NavigableSet<E> navigableSet(
      NavigableSet<E> navigableSet, @CheckForNull Object mutex) {
    return new SynchronizedNavigableSet<>(navigableSet, mutex);
  }

  @GwtIncompatible // NavigableSet
  static <E extends @Nullable Object> NavigableSet<E> navigableSet(NavigableSet<E> navigableSet) {
    return navigableSet(navigableSet, null);

  }

  @GwtIncompatible // NavigableSet
  static <E extends @Nullable Object> NavigableSet<E> navigableSet(
      NavigableSet<E> navigableSet, @CheckForNull Object mutex) {
    return new SynchronizedNavigableSet<>(navigableSet, mutex);
  }

  @GwtIncompatible // NavigableSet
  static <E extends @Nullable Object> NavigableSet<E> navigableSet(NavigableSet<E> navigableSet) {
    return navigableSet(navigableSet, null);

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

  /**
   * {@inheritDoc}
   *
   * <p>Because a {@code TreeMultimap} has unique sorted keys, this method returns a {@link
   * NavigableSet}, instead of the {@link java.util.Set} specified in the {@link Multimap}
   * interface.

    }
  }

  @GwtIncompatible // NavigableSet
  private static class FilteredNavigableSet<E extends @Nullable Object> extends FilteredSortedSet<E>
      implements NavigableSet<E> {
    FilteredNavigableSet(NavigableSet<E> unfiltered, Predicate<? super E> predicate) {
      super(unfiltered, predicate);
    }

    NavigableSet<E> unfiltered() {
      return (NavigableSet<E>) unfiltered;
    }

    @Override

  @Override
  public Comparator<? super E> comparator() {
    return delegate().comparator();
  }

  @Override
  NavigableSet<E> createElementSet() {
    return unmodifiableNavigableSet(delegate().elementSet());
  }

  @Override
  public NavigableSet<E> elementSet() {
    return (NavigableSet<E>) super.elementSet();
  }

  @LazyInit @CheckForNull private transient UnmodifiableSortedMultiset<E> descendingMultiset;

    this.domain = domain;
  }

  @Override
  public ContiguousSet<C> headSet(C toElement) {
    return headSetImpl(checkNotNull(toElement), false);
  }

  /** @since 12.0 */
  @GwtIncompatible // NavigableSet
  @Override
  public ContiguousSet<C> headSet(C toElement, boolean inclusive) {
    return headSetImpl(checkNotNull(toElement), inclusive);
  }

  @Override

  public Test testsForCheckedNavigableSet() {
    return SortedSetTestSuiteBuilder.using(
            new TestStringSortedSetGenerator() {
              @Override
              public NavigableSet<String> create(String[] elements) {
                NavigableSet<String> innerSet = new TreeSet<>();
                Collections.addAll(innerSet, elements);
                return Collections.checkedNavigableSet(innerSet, String.class);
              }

      Collection<E> collection) {
    if (collection instanceof NavigableSet) {
      return unmodifiableNavigableSet((NavigableSet<E>) collection);
    } else {
      return unmodifiableSortedSet((SortedSet<E>) collection);
    }
  }

  @Override
  Collection<V> wrapCollection(@ParametricNullness K key, Collection<V> collection) {
    if (collection instanceof NavigableSet) {