A metadata plugin for isbnlib (https://pypi.python.org/pypi/isbnlib) using the service BnF Catalogue General (for books in french).
To install, from the command line, enter (in some cases you have to precede the command with sudo):
$ pip install isbnlib-bnf
After install, a new metadata provider (bnf) is available in isbnlib.
For available plugins check here.