Is there any way to add easily the postal codes to the package?

[goromachine]

I've seen on django-cities that there is a postal code, but searching here on django-cities-light I've seen that are not here.
so my question is if it's possible to add the postal codes easily to the package. I like how easy to use is this package in front of django-cities, so I would like to maintain it but being able to add postal codes.
I'm not experienced with geonames at all, so which should be the easiest way to do this for me?
Any alternative solution?
Thank you.