Extending g-ir bindings

[David Nečas <yeti physics muni cz>]

Hello, I have a library with some GObject-derived classes, have
generated the gir and typelib using g-ir, can import it from
gi.repository in python and it works.

Now I'd like my classes to do things such as support the Py_Buffer
interface (or other interfaces).  What is the least painful way how to
achieve this?

Thanks,

Yeti