abstract class AncTree {

  abstract int size();

  abstract java.util.List<String> allNames( /* AncTree this */ );

  /* Representing union-types by using classes
   * is called the 'composite design pattern'.
   * (And usually it's not recognized that they're taking the 
   *  union of two different types(sets).)
   * See for example:
   *     http://sourcemaking.com/design_patterns/composite
   */
  
  
  
  
  /** Some test cases for AncTrees.
   * @param args -- ignored.
   */
  public static void main( String[] args ) {
    AncTree abe   = new Child( "Abe",   1920, "brown", new Unknown(), new Unknown() );
    AncTree mona  = new Child( "Mona",  1929, "blue",  new Unknown(), new Unknown() );
    AncTree homer = new Child( "Homer", 1955, "brown", mona, abe );
    AncTree bart  = new Child( "Bart",  1956, "brown", 
                               new Child( "Marge", 1953, "blue",
                                          new Child( "Jackie", 1926, "brown", new Unknown(), new Unknown() ),
                                          new Unknown() ),
                               homer );

    System.out.println( "Actual: " + (new Unknown()).size() );
    System.out.println( "Expect: " + 0);
    System.out.println( "Actual: " + abe.size() );
    System.out.println( "Expect: " + 1);
    System.out.println( "Actual: " + homer.size() );
    System.out.println( "Expect: " + 3);
    System.out.println( "Actual: " + bart.size() );
    System.out.println( "Expect: " + 6);
    
    System.out.println( "Actual: " + homer.allNames() );
    System.out.println( "Expect: " + java.util.Arrays.asList("Mona","Homer","Abe") );
    System.out.println( "Actual: " + bart.allNames() );
    System.out.println( "Expect: " + java.util.Arrays.asList("Jackie", "Marge", "Bart", "Mona","Homer","Abe") );
    
    //System.out.println( "Actual: " + homer.entitle() );
    //System.out.println( "Expect: " + homer.entitle() );

    
/*
    System.out.println( "Actual: " + abe.toString() );
    System.out.println( "Expect: " + "new Child( \"Abe\", 1920, \"brown\", new Unknown(), new Unknown() )" );

    System.out.println( "Actual: " + homer.toString() );
    System.out.println( "Expect: " + "??" ); 
    */
    }

 }