/** Leaf node: a node with no subtrees. 
 *
 *  Taken from Core Web Programming from 
 *  Prentice Hall and Sun Microsystems Press,
 *  http://www.corewebprogramming.com/.
 *  © 2001 Marty Hall and Larry Brown;
 *  may be freely used or adapted. 
 */

public class Leaf extends Node {
  public Leaf(Object value) {
    super(value, null, null);
  }
}