ImmutableSortedSet<E> set = headSet(e, true);
    return !set.isEmpty() ? set.last() : null;
  }

  public ImmutableSortedSet<E> headSet(E toElement, boolean inclusive) {
    checkNotNull(toElement);
    if (inclusive) {
      E tmp = higher(toElement);
      if (tmp == null) {
        return this;
      }
      toElement = tmp;
    }
    return headSet(toElement);
  }

    @Override
    public NavigableSet<E> headSet(@ParametricNullness E toElement, boolean inclusive) {
      return filter(unfiltered().headSet(toElement, inclusive), predicate);
    }

    @Override
    public NavigableSet<E> tailSet(@ParametricNullness E fromElement, boolean inclusive) {
      return filter(unfiltered().tailSet(fromElement, inclusive), predicate);
    }
  }

  /**

   * value} is greater than {@code max}, {@code max} is returned.
   *
   * @param value the {@code char} value to constrain
   * @param min the lower bound (inclusive) of the range to constrain {@code value} to
   * @param max the upper bound (inclusive) of the range to constrain {@code value} to
   * @throws IllegalArgumentException if {@code min > max}
   * @since 21.0
   */

   * value} is greater than {@code max}, {@code max} is returned.
   *
   * @param value the {@code short} value to constrain
   * @param min the lower bound (inclusive) of the range to constrain {@code value} to
   * @param max the upper bound (inclusive) of the range to constrain {@code value} to
   * @throws IllegalArgumentException if {@code min > max}
   * @since 21.0
   */

   * value} is greater than {@code max}, {@code max} is returned.
   *
   * @param value the {@code short} value to constrain
   * @param min the lower bound (inclusive) of the range to constrain {@code value} to
   * @param max the upper bound (inclusive) of the range to constrain {@code value} to
   * @throws IllegalArgumentException if {@code min > max}
   * @since 21.0
   */

     *
     * @param ctype2
     *            The array of character types.
     * @param low
     *            The lower bound of the character range (inclusive).
     * @param hi
     *            The upper bound of the character range (inclusive).
     */
    protected static void wordChars(final byte[] ctype2, int low, int hi) {
        if (low < 0) {
            low = 0;
        }

  public ImmutableSortedMap<K, V> headMap(K toKey) {
    checkNotNull(toKey);
    return newView(sortedDelegate.headMap(toKey));
  }

  ImmutableSortedMap<K, V> headMap(K toKey, boolean inclusive) {
    checkNotNull(toKey);
    if (inclusive) {
      K tmp = higher(toKey);
      if (tmp == null) {
        return this;
      }
      toKey = tmp;
    }
    return headMap(toKey);
  }

  @Override

   */
  @Override
  public ImmutableSortedSet<E> tailSet(E fromElement, boolean inclusive) {
    return tailSetImpl(checkNotNull(fromElement), inclusive);
  }

  /*
   * These methods perform most headSet, subSet, and tailSet logic, besides
   * parameter validation.
   */
  abstract ImmutableSortedSet<E> headSetImpl(E toElement, boolean inclusive);

  abstract ImmutableSortedSet<E> subSetImpl(

   */
  private static long flip(long a) {
    return a ^ Long.MIN_VALUE;
  }

  /**
   * Compares the two specified {@code long} values, treating them as unsigned values between {@code
   * 0} and {@code 2^64 - 1} inclusive.
   *
   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated; use the
   * equivalent {@link Long#compareUnsigned(long, long)} method instead.
   *

   * constraining a {@code long} input to an {@code int} range.
   *
   * @param value the {@code int} value to constrain
   * @param min the lower bound (inclusive) of the range to constrain {@code value} to
   * @param max the upper bound (inclusive) of the range to constrain {@code value} to
   * @throws IllegalArgumentException if {@code min > max}
   * @since 21.0
   */