regular expression example generator

[John Farrell]

I have a faint recollection of hearing somewhere that someone for some
language had written some software which took a regular expression and
generated for you the types of things that would match it. For example,

'(a(b)?)?c' would give you 'c', 'abc', 'ac'

(ab)* would give you '', 'ab', 'abab'

IMHO this would be useful for debugging REs when they get complicated.
Has anyone heard of such a thing for Python? Thanks,

John