/*
   +----------+     
   |GBSBook   |     
   +----------+   
   +----------+   
*/   

//a predicate to select books wirtten by George Bernard Shaw
class GBSBook implements ISelect{

  GBSBook(){};

  //is the given book written by GBS   
  public boolean select(Object obj){ 
    return (((Book)obj).author.equals("GBS")); 
  } 
}