*/
  @SuppressWarnings("rawtypes") // https://github.com/google/guava/issues/989
  public static <E extends Comparable> TreeSet<E> newTreeSet(Iterable<? extends E> elements) {
    TreeSet<E> set = newTreeSet();
    Iterables.addAll(set, elements);
    return set;
  }

  /**
   * Creates a <i>mutable</i>, empty {@code TreeSet} instance with the given comparator.
   *

   * only when the resulting list may need further modification, or may contain {@code null}. The
   * input is not modified. The returned list is serializable and has random access.
   *
   * <p>Unlike {@link Sets#newTreeSet(Iterable)}, this method does not discard elements that are
   * duplicates according to the comparator. The sort performed is <i>stable</i>, meaning that such