[Zope-dev] Intersection (set) in Zope

Does anyone know if Zope already has (I'll bet it does, it's just a matter of finding it, which I haven't yet) an object or method for intersection or set of two lists. I want items common to both lists. It's a simple python external method, but why write code t hat's already written. I combed the dtml guide and the source in places and can't see what it would be called. Any ideas? Jason Spisak webmaster@mtear.com