[web2py] What is the simplest/most elegent way to get rid of spaces in XML tags

[Kemaru]

Dear all,

If I use the build-in XML render on the following data:

{'San Jose' : 37}

I get the following XML file:

...
<San Jose>37</San Jose>
...

I am wondering if I can tell the build-in XML render to replace spaces with 
underscores?

I have searched this group but found no solution. Thanks a lot in advance.