how to "source" a file?

[Mark Harrison]

I have a set of configuration files that are expressed in
python.  Users can set up triggers and callbacks as
python function calls.

Some of these functions have become shared between several
products, so I would like to factor out these functions into
a separate file.

Can someone give me a clue as to the best way to proceed?
I'm trying various combinations of import, but with no success.

Can someone loan me a clue?

Many TIA,
Mark

-- 
Mark Harrison
Pixar Animation studios