*     intersection
   * @since 27.0
   */
  public Range<C> gap(Range<C> otherRange) {
    /*
     * For an explanation of the basic principle behind this check, see
     * https://stackoverflow.com/a/35754308/28465
     *
     * In that explanation's notation, our `overlap` check would be `x1 < y2 && y1 < x2`. We've