anchor.diff:    void processRequest(PurchaseRequest request) {
       if (request.amount < _allowable) {
         print("President will approve $request");
  +      return;
       }
  -    else {
  -      print("Your request for $request needs a board meeting!");
  -    }
  +    super.processRequest(request);
     }
   }
   
  
positive.code:   void processRequest(PurchaseRequest request) {
      if (request.amount < _allowable) {
        print("Manager will approve $request.");
      }
      else if (_successor != null) {
        _successor.processRequest(request);
      }
    }
  }
  
  
negative.code:   void processRequest(PurchaseRequest request) {
      if (request.amount < _allowable) {
        print("Vice President will approve $request");
        return;
      }
      super.processRequest(request);
    }
  }
  
  