Currently, sloccount only recognizes files with the extension .py
as python code.  Adding pyx as another possible
extension whcih contains python code makes the numbers
of a project of mine more accurate.

x4:~/src/a11y/brltty% find . -name \*.py\* -exec wc -l {} \;
40 ./Bindings/Python/setup.py
702 ./Bindings/Python/brlapi.pyx
40 ./Bindings/Python/setup.py.in
26 ./Bindings/Python/mkdoc.py

While pyx is actually binding code, it follows python syntax and should
be consider python.

The modification is simple enough:

x4:/tmp/sloccount-2.26% grep -n pyx break_filelist
180:  "py" => "python", "pyx" => "python",