[xslt] Contexts? Tutorial? Example? :)

["Michael Rothwell" <rothwell holly-springs nc us>]

I'm wondering if there is a guide to using contexts with libxml and libxslt.
The tutorial shows only the simple case. I've read through the API
documentation, but would like to also see a recipe for the "right way" to
use contexts... if someone has one handy...

-Michael