I forked cpython and implemented an lwalk function on os.py. The lwalk funtion behaves exactly like walk(), except that it recurses only to a certain level of depth that can be selected by the user. More information on the lwalk function can be found on "os.py" in my cpython fork. It worked fine when I tested the funtion in a local virtual environment, but when I installed Python 3.7 with my lwalk function implemented in os.py I get an error when I try to test it in my recent Python installation: "TypeError: 'NoneType' object is not iterable".
I'd like to know where else I need to add info about my lwalk function so it can be correctly used in a fresh Python installation and so than I can send a Pull Request.