[Zope] objectmanager contains object test

this is probably really simple, but I can't figure it out from the API docs. I want to test to see if a folder contains a dtml method with a known id. how do I do this from python? I've tried if context.data.news[ object_id ] which breaks with a key error, if it doesn't exist. I want something like context.data.news.has_key( object_id ) but object manager doesn't seem to have any methods like that. and doing a try, and catching key errors seems a messy way to do it.