What prevents id collisions in Zope? It looks like the the ObjectManager.py code checks to see if the id is taken, and then it reserves the id. Is there a danger that 2 processes/threads (z2.py -t 4?) could both check and reserve the same id? Is there something in Zope that prevents this (improbable, but perhaps possible) problem? Is there certain way to find an object id that is not taken?