sphinx-apidoc to identify file types other than .py

Question

I built a language expansion for Python 3, which allows its users to generate Python files with '.pytsl' suffix. I want to use Sphinx for documenting those files. However, when running sphinx-apidoc on a specific directory, the '.py' files under that directory get translated to '.rst', while the '.pytsl' files don't.

I searched in the documentation for sphinx-apidoc and in the help section, but couldn't find a way that allows me to enable sphinx-apidoc to identify files with an extension other than '.py'.

Is there a way to do this? If not, can this be supported?