Is this still being developed? The last commit to the main library was 5 months ago and its tied to exceptions/tests.
https://news.ycombinator.com/item?id=38659315
A lot of people seemed to move to nbdev which tried to improve on many aspects of notebook dev culture, but nbdev's maintainers include GitHub employees who are can only comprehend doing anything via GitHub integrations and get huffy and how-dare-you-take-that-tone-with-us if you ever ask about how you would go about doing something without relying on GitHub.
So personally I've just been focusing on nbconvert and rolling my own things.
also, if it isn't maintained by the company that made it, then it is a good sign that they are no longer using it. it suggests that there is a better solution elsewhere.