[Zope] How to obtain the parent-object from an Zope-object

[Wim Bekker]

How can I obtain the 'parent' object in Zope with python (script)?

I have a subfolder that contains some python script that I want to run on
some selected objects from the parent folder (of this subfolder).

I can go a level down by using object from self.objectValues(). But how do I
go one level up?

I cannot find this kind of information anywhere.

Wim