}

  @Override
  ImmutableSortedSet<E> subSetImpl(
      E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
    return tailSetImpl(fromElement, fromInclusive).headSetImpl(toElement, toInclusive);
  }

  @Override
  ImmutableSortedSet<E> tailSetImpl(E fromElement, boolean inclusive) {
    return getSubSet(tailIndex(fromElement, inclusive), size());
  }

          Range.range(
              fromElement, BoundType.forBoolean(fromInclusive),
              toElement, BoundType.forBoolean(toInclusive)));
    }

    @Override
    ImmutableSortedSet<C> tailSetImpl(C fromElement, boolean inclusive) {
      return subSet(Range.downTo(fromElement, BoundType.forBoolean(inclusive)));
    }

    @Override
    public boolean contains(@Nullable Object o) {
      if (o == null) {