Consider the following analogy for the concept of caching. A serviceman comes to a house to repair the heating system. He carries a toolbox that contains a number of tools that he has used recently in similar jobs. He uses these tools repeatedly, until he reaches a point where other tools are needed. It is likely that he has the required tools in his truck outside the house. But, if the needed tools are not in the truck, he must go to his shop to get them.

Suppose we argue that the toolbox, the truck, and the shop correspond to the L1 cache, the L2 cache, and the main memory of a computer. How good is this analogy? Discuss its correct and incorrect features.