/* Not only is this Honkable (because every AbstractHonkable
 * is Honkable), but we barely have to write anything, because
 * the AbstractHonkable does most of the work.
 * We've "enforced behavior" by relying on AbstractHonkable.
 */
class Car extends AbstractHonkable {
  public Car() {
    honkTxt = "honk! ";
  }
}