New open e-book "Teaching and Learning with Jupyter"

Just ran across and briefly glanced over this new and very nice open (source) e-book ( Kudos to @willingc and the rest of the authoring team. I especially like lots of pedagogical wisdom, even though that aspect is quite tangential to my current involvement in Jupyter-related efforts. Obviously, it is quite a subjective preference, but I prefer the PDF version of the book (though it is great that there is a choice in the output format). Another interesting feature of this project is its use of the bookdown R package ( instead of more traditional options like Sphinx or GitBook (feel free to comment on rationale for the selected choice).