// TODO(kevinb): right way to explain this??
  // plus https://github.com/google/guava/issues/989
  public static <C extends Comparable> Ordering<C> natural() {
    return (Ordering<C>) NaturalOrdering.INSTANCE;
  }

  // Static factories

  /**
   * Returns an ordering based on an <i>existing</i> comparator instance. Note that it is