Python OS. Walk (...)

I used to write some Python command line gadgets to simplify some repetitive work in my work. In this case, I had to traverse a directory. I had been writing recursion.ProgramTwo days ago, I discovered that there was a ready-made class library in Python.
This function is OS. Walk (top [, topdown = true [, onerror = none [, followlinks = false]).
Usage:

Import OS <br/> for root, dirs, files in OS. walk ('/opt /'): <br/> Print root # root of the directory currently traversed <br/> Print dirs # all directories under the root of the directory currently traversed <br/> print files # current all files under the root of the directory to be traversed