How to write a sphinx extension that integrates gettext functionalities for translation ?

[yguel]

I try to update the sphinx-exercise extension to have title and subtitle integrated as gettext strings for internationalization. Sadly I cannot make it work.
I am looking for a tutorial on how to write sphinx extension with internationalization support (ideally gettext) or a well written extension that already integrate such a feature to learn from it and replicate the result for sphinx-exercise.