addon folder path?

I want to include a .blend with my addon to store some node groups without constructing them node by node via python (due to their number, complexity and ease of editing).

Is there a function that will always point me at the folder where my addon is (so I can append my node groups) that doesn’t depend on the OS?

Alternatively, is there a way I can serialize a nodegroup and load it back?

You can find the path to the addons folder with bpy.utils.script_paths

file should point to your addon folder