[mod_python] mod_xslt filtering of mod_python output

Hi. I'm a a beginner with mod_python, and I'm trying to use mod_python
and mod_xslt together.

mod_python gets called via a "SetHandler python-program", and inside
python I set the content-type to text/xml.

mod_xslt is called via "AddOutputFilterByType mod-xslt "text/xml")  

--- httpd.conf stanza: ---

<Location /the_dir>
    SetHandler python-program
    PythonPath "sys.path + ['/path/']"
    PythonHandler mymodule
    AddOutputFilterByType mod-xslt text/xml
</Location>
--- end ---

--- /path/mymodule.py excerpt ---

def handler(req):
        
  ... generate xml, place in out ...

  req.content_type = "text/xml"
  req.write(out)
  return apache.OK
--- end ---

Both work fine standalone - mod_xslt filters xml files, and mod_python
is generating dynamic content, but I don't know how to get mod_xslt to
filter dynamic content from mod_python...

What am I missing?  

Apache 2.0.40, mod_python 3.0.0, python 2.2.1 (all stock installs on on
RH 8) mod_xslt 1.0.5 (built locally)