How do I print multiple books from command line

The command line help says

-b BOOKS, --books BOOKS
                        Reference list to print (as in Choose Books)

in the github code, I also found documentation that says

-b BOOKS, --books BOOKS
                        Space separated bookid list to set

both of those would suggest that I just write the book abbreviations. But if I do this
python ptxprint -b JAS 1PE -P
I get
and if I do this
python ptxprint -b JAS 1PE 2PE -P
I get
ptxprint: error: unrecognized arguments: 2PE

  1. What is the correct syntax?
  2. What does res=0 mean? (I’ve seen that while trying to install ptxprint on a new Linux machine also.)

My best guess is that if you want to do multiple books, you’ll need to put the list of books in quotes:

python ptxprint -b "JAS 1PE 2PE" -P

res=0 means that the program completed successfully without any errors (any number other than 0, like res=1, or res=2 indicates that something failed).

Thank you. The quotes did the trick.