[mod_python] processing checkbox field from form

I am beginner on python and mod_python.

When I have form without checkbox field, everythig is OK. I use
publisher and get fields as parameters of function.

But when I add checkbox field I get to trouble. Number of parameters
is changing. In html documentation I found: "Unselected checkboxes and
radio buttons do not return name/value pairs when the form is
submitted." 

I don't know how write function for processing this parameters from
that form.

Is somewhere any example for my problem?

thanks

warning: my english is poor
--
        Jiří Lisický                      ČD KMŽP Olomouc
e-mail: lisicky at datis.cdrail.cz           Vídeňská 15
 phone: +420-068-472-2272                 Olomouc, Czech Republic
              >>> čeština ISO-8859-2 Compatible <<<