I'm a newbie zopista, and python for that matter... In brief: I get a NameError when invoking "filter(...)" from DTML. I thought this was a built-in python method, so I'm a bit puzzled. In detail: 1) I want to display a dtml-tree of my folder hierarchy, but I want to exclude all Zwiki discussion groups. 2) In my index_html for the top level folder, I have the following: <dtml-tree Outline leaves=dtcTemplate > <SPAN CLASS="tree"> <dtml-if tree-item-expanded> <dtml-if expr="objectValues(['Folder'])"> <IMG SRC="<dtml-var BASE2>/Outline/OpenBook.gif" ALIGN="TOP" BORDER="0"> </dtml-if> <STRONG> <I><dtml-var title></I> </STRONG> <dtml-else> <dtml-if expr="objectValues(['Folder'])"> <IMG SRC="<dtml-var BASE2>/Outline/ClosedBook.gif" ALIGN="TOP" BORDER="0"> </dtml-if> <dtml-var title> </dtml-if> </SPAN> </dtml-tree> which is cribbed straight from QuickStart. 3) I only want to ignore Zwiki groups, but they are out-of-the-box folders, so I can't filter on meta-class. 4) My approach is just to add a property to the Zwiki folder ('blockTreeBranching') 5) In the dtml-tree tag, I change it to: <dtml-tree Technical leaves=dtcTemplate branches_expr="filter( lambda f: not f.hasProperty('blockTreeBranching', false), objectValues(['Folder']) )"> which, all things equal, should DoTheRightThang. 6) The code can be published, but when I view it, it spits out a NameError, choking on "filter". Argh. Ideas gratefully recieved... Nick HyperSpace Ltd,Birmingham Research Park, Edgbaston, UK, B15 2SQ (e) hyperspace@btinternet.com (t) +44 (0)121 414 7019