[tryton] what is the proper way of filling the (empty) list of vat countries from a custom module?

[Mariano Ramon]

I can see that that list is hardcoded in the party.py file and starts 
empty. and is a list defined outside any class, how do I get to that scope 
from a module to overwrite it?
or better yet is there any better way to modify that list than directly in 
the code?
why starts empty?

Thanks