Python style question

[Martin Pool]

Since we seem to have some experienced pythonists here:

I have a factory, find_branch, which can return instances of Branch or
RemoteBranch depending on a parameter.  (Perhaps it should return
Branches which contain a BranchStorage of various types, but ignore
that for the moment.)  What is good Python style for an abstract
factory?

One way is a simple function, as here.  Another way is a static method
like Branch.open().  I suppose one might also override the call method
for Branch so that it possibly constructs a subclass(?)

The function works fine but I just wondered if there were any comments
on idioms that work well?

-- 
Martin