[lxml-dev] xpath check, selective xslt

Hi everybody, a couple of questions: 1) is it possible to check if an element is selected by a particular xpath expression -without- checking if the element is part of the whole node-set returned by the expression evaluation? 2) let's assume we have an xslt-transformed ElementTree and that we add an untransformed branch to it. Is it possible to apply the same xslt transformation selectively, only to the added branch but not to the rest of the tree? Of course this wouldn't help in those situation where transformed(tree+branch) != transformed(tree) + transformed(branch). But excluding those cases, is there a way to do it? Thanks for your help! Manu