Reads the `nbk` files a Kindle Scribe writes and renders them as vector PDFs, complete with the ruled or squared background the notes were written on, and adds what was written on a PDF on the device to a copy of that PDF. Includes a reader for the signature container the device wraps its SQLite database in, a binary Amazon Ion parser, and a decoder for the second-order delta encoding the firmware stores pen strokes in. Ships the `nbk2pdf` command line tool.