DList list = new DList();
list.add( "D" );
list.add( "C" );
list.add( "C" );
list.add( "B" );
list.add( "A" );
list.add( "A" );
System.out.println( "list = " + list );
list.unique();
System.out.println( "list = " + list );
list.reverse();
System.out.println( "list = " + list );