Sharing a method (function) among several objects.

[Diez B. Roggisch]

> Since they are not the same or similar, it's not logical to use a
> common superclass.

As python supports multiple inheritance, it's very well "logical" to do it
by subclassing.

> 
> So I'm asking, what's a good way to allow those objects to share that
> function?
> 
> The best solution I've found so far is to put that function in a
> module, and have all objects import and use it. But I doubt that's a
> good use-case for modules; writing and importing a module that contains
> just a single function seems like an abuse.

A module is a unit of code that (should) encapsulate a certain
functionality. So it's perfect for your needs. There is no law or even rule
of thumb that makes claims about module size (or the lack of, for this
matter). So create a module - it doesn't cost you anything. 
-- 
Regards,

Diez B. Roggisch