Include in, and/or use isbnlib ?
see https://github.com/xlcnd/isbnlib/issues/28#issuecomment-242407867
edit 2023: see the list of codes -> country O_o https://github.com/xlcnd/isbnlib/blob/dev/isbnlib/_data/data4info.py Prob not the scope of this project though.
Edited by vindarel