isort

Is there a how-to guide to write my own tool? I want to do some conditional stripping/modifying (e.g. insert a Python script into a cell) for a Kaggle notebook. I've been playing around for an hour and I've sort-of-got a tool working, but I can't get nbqa to pass in anything I can read. In my code sys.argv has the original Notebook filename and if I rewrite that, nbqa throws an exception.k

Currently the whole buffer gets deleted, and no error is shown... That's a really bad UX