}

  ImmutableSortedMultiset<E> getSubMultiset(int from, int to) {
    checkPositionIndexes(from, to, length);
    if (from == to) {
      return emptyMultiset(comparator());
    } else if (from == 0 && to == length) {
      return this;
    } else {
      RegularImmutableSortedSet<E> subElementSet = elementSet.getSubSet(from, to);