/*
             +---------------------------+                
             |    ISelect                |                
             +---------------------------+
             | boolean select(Object obj)|		
		     +---------------------------+                
                         |                    
                        / \                   
                        ---                   
                         |                    
              ----------------------------          
              |            |             |          
        +----------+   +---------+   +---------+  
        | LongSong |   | GBSbook |   | OldBook |  
        +----------+   +---------+   +---------+
        +----------+   +---------+   |int year |
                                     +---------*
*/

interface ISelect{
  
  // does the given object satisfy this predicate?
  boolean select(Object obj);
}