Question about asksaveasfilename

[Mike Callahan]

I am using asksaveasfilename from tkFileDialog. I want to restrict my users
to save filenames with these extensions .unl or .sql. This is my call:

from tkFileDialog import asksaveasfilename
fn = asksaveasfilename(filetypes=[('Unloaded', '*.unl'),
('Queries','*.sql')])

This gives me the correct dialog box, but how do I force the correct
extension on fn?  Thanks.

Mike C.