The ISBN validation data in isbn.py have not been updated since September 2007. The ISBN ranges are updated regularly, meaning the isbn.py script is currently wrong. Rather than keeping this data up to date, the algorithm in isbn.py should be replaced with an external package which provides the same functionality and is py3 compatible, packaged on pypi, and is regularly updated as the ISBN ranges are issued and modified.
There are several such packages on pypi. See
The most useful is
Also up to date:
Ideally isbn is able to use whichever library is installed.