[mod_python] select multiple

hi

I use publisher handler. When I do:
for k in req.form.keys():
    req.write(repr(k)+" - "+repr(req.form[k])+"\n")

it does not show list of lists at "select multiple"!
just 'manufacturers' - ['13', '18', '14', '17', '13', '14', '17'] not
'manufacturers' - [['13', '18'], ['14', '17', '13'], ['14', '17']]

why?

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WBR, sector119