public NavigableSet<E> headSet(E toElement, boolean inclusive) {
    return new SafeTreeSet<>(delegate.headSet(checkValid(toElement), inclusive));
  }

  @Override
  public @Nullable E higher(E e) {
    return delegate.higher(checkValid(e));
  }

  @Override
  public boolean isEmpty() {
    return delegate.isEmpty();
  }

  @Override
  public Iterator<E> iterator() {
    return delegate.iterator();

            KeyPresentBehavior.FIRST_AFTER,
            KeyAbsentBehavior.NEXT_HIGHER);
    int upperIndex =
        SortedLists.binarySearch(
            ranges,
            Range::lowerBound,
            range.upperBound,
            KeyPresentBehavior.ANY_PRESENT,
            KeyAbsentBehavior.NEXT_HIGHER);
    if (lowerIndex >= upperIndex) {
      return ImmutableRangeMap.of();
    }

  @CheckForNull
  public E ceiling(E element) {
    int index = tailIndex(element, true);
    return (index == size()) ? null : elements.get(index);
  }

  @Override
  @CheckForNull
  public E higher(E element) {
    int index = tailIndex(element, false);
    return (index == size()) ? null : elements.get(index);
  }

  @Override
  ImmutableSortedSet<E> headSetImpl(E toElement, boolean inclusive) {

    verifyTableSize(60, 60, 128);
    verifyTableSize(120, 60, 256);
    // if the table is only double the necessary size, we don't bother resizing it
    verifyTableSize(180, 60, 128);
    // but if it's even bigger than double, we rebuild the table
    verifyTableSize(17, 17, 32);
    verifyTableSize(17, 16, 32);
    verifyTableSize(17, 15, 32);
  }

  @GwtIncompatible // RegularImmutableSet.table not in emulation

   *     neither fast nor secure. As of January 2017, we suggest:
   *     <ul>
   *       <li>For security:
   *           {@link Hashing#sha256} or a higher-level API.
   *       <li>For speed: {@link Hashing#goodFastHash}, though see its docs for caveats.
   *     </ul>
   */
  @Deprecated
  public static HashFunction md5() {
    return Md5Holder.MD5;
  }

    assertEquals(
        "Modifying the builder should not have changed any already built sets",
        216,
        webSafeColors.size());
    assertEquals("the new array should be one bigger than webSafeColors", 217, addedColor.size());
    Integer[] appendColorArray = addedColor.toArray(new Integer[addedColor.size()]);
    assertEquals(getComplexBuilderSetLastElement(), (int) appendColorArray[216]);
  }

    assertEquals(
        "Modifying the builder should not have changed any already built sets",
        216,
        webSafeColors.size());
    assertEquals("the new array should be one bigger than webSafeColors", 217, addedColor.size());
    Integer[] appendColorArray = addedColor.toArray(new Integer[addedColor.size()]);
    assertEquals(getComplexBuilderSetLastElement(), (int) appendColorArray[216]);
  }

  }

  @VisibleForTesting
  @WeakOuter
  final class ValueSet extends Sets.ImprovedAbstractSet<V> implements ValueSetLink<K, V> {
    /*
     * We currently use a fixed load factor of 1.0, a bit higher than normal to reduce memory
     * consumption.
     */

    @ParametricNullness private final K key;
    @VisibleForTesting @Nullable ValueEntry<K, V>[] hashTable;
    private int size = 0;

   * {@code checkedPow(2, log2(x, CEILING))}.
   *
   * @throws IllegalArgumentException if {@code x <= 0}
   * @throws ArithmeticException of the next-higher power of two is not representable as a {@code
   *     long}, i.e. when {@code x > 2^62}
   * @since 20.0
   */
  public static long ceilingPowerOfTwo(long x) {
    checkPositive("x", x);

  public E ceiling(E e) {
    return Iterables.<@Nullable E>getFirst(tailSet(e, true), null);
  }

  /** @since 12.0 */
  @GwtIncompatible // NavigableSet
  @Override
  @CheckForNull
  public E higher(E e) {
    return Iterables.<@Nullable E>getFirst(tailSet(e, false), null);
  }

  @Override
  public E first() {
    return iterator().next();
  }

  @Override
  public E last() {