Memoizing a function adds a transparent caching wrapper to the function, so that function values that have already been obtained are returned from a cache rather than being rebuilt each time.
记忆一个功能将为功能添加一个透明的缓存封装，因此已经得到的值将从缓存中返回而不是每次都重建。
2
Since any change on the NFS server is not desirable, internally this wrapper performs separate mounts on the client machine that are transparent to the user.