[mod_python] Python Server Pages debugging security

Hi guys,
you're probably through with this, but I'd like to ask (google didn't tell  
me anything).

How can I prevent people from viewing my PSP source via appending an  
underscore to the filename? (you know what I mean...I write index.psp_  
instead of index.psp and get the two-column output with PSP and Python  
source).
Is is possible to do it with some Apache directive?

Thanx for advice!
Dan