Since programs are often long-lived (they can last for years or decades), it is customary to break them into stages, or time boxes focused on a specific delivery of business value.
The doorbell rings, giving Michael a much needed break from the project. He opens the door for a delivery girl.
门铃响了，正好给了Michael一个必需的休息间隙，他打开了门，是个送比萨饼的女孩。
3
Break the trick: in the magic View seller if sold payment, such as the seller has paid the order display a blue shipping button, the buyer paid to delivery.