[Zope] ZPT-How to sort by type and then title or id

I wanted to create a listing for a folder that sorted first by the type of item and secondly by title. I found this example for sorting by title, but I can't figure out how to get it to sort by type first. Any guidance is appreciated... <tal:block define="item python:here.getFolderContents(suppressHiddenFiles=1); dummy python:item.sort(lambda a,b:cmp(a.title_or_id(), b.title_or_id()))" tal:repeat="items item">