1    package model; 
2     
3    class CashPayment { 
4        private int coins; 
5         
6        void insert() { coins++; } 
7         
8        boolean enough(int value) { 
9            return coins >= value; 
10       } 
11        
12       int deduct(int value) { 
13           int change = coins - value; 
14           coins = 0; 
15           return change; 
16       } 
17        
18       int cancel() { 
19           return deduct(0); 
20       } 
21   }