Hi @adkelley, thank you for your comment and apologies for the late reply. Please follow the instructions in the book.
The modules_1, modules_2 (etc.) folders are different versions of the modules folder as the chapter progresses. We are aware of the confusion that the current code folder might be generating and we are trying to update that on the prag prog side, but we are having some issues because the book was already on it way to its final print version. We’ll shortly make a public repo containing the examples of the book following a folder structure that we hope will make more sense to you.
But in the meantime, please follow the instructions in the book itself.
Thanks!