關(guān)于本節(jié)的比如黑板擦來說，也是奴此。編程者的初始反應(yīng)是它與起動一臺機器或改動一個方式不一樣。然而，假如忽略實踐使用，只研究目標(biāo)運轉(zhuǎn)所要求的事件或序列，那么在這些不同的使用中能提取出相似之處。
這個意圖不能獨登時達(dá)到，由于實踐問題確實訪礙某些抱負(fù)操作的發(fā)作。要記住的是，觀察一個問題的方法不止一種，這個十分言簡意賅的擦黑板程序就是其中一種方法。

About this section, such as blackboard eraser, it is also slave this. The initial reaction of the programmer is that it is different from starting a machine or changing a way. However, if we ignore the practical use and only study the events or sequences required by the target operation, we can extract similarities in these different uses.
This intention cannot be achieved immediately alone, because practical problems do hinder the onset of some ambitious operations. Remember that there are more than one ways to observe a problem, and this very concise blackboard cleaning program is one of them.