[Zope] How to Add an object at the root of a zope tree

[D2]

How to add an object at the root of a Zope tree even if the method has 
been called inside a subfolder ?

I tried location=aq_parent(getattr(self, 'Control_Panel'))
it returns the folder where is located the method. (I suppose that 
'Control_Panel' is acquired)

I tried : location=aq_parent(aq_inner(getattr(self, 'Control_Panel')))
It raises an error : 'aq_parent is not defined'. It's the same with aq_base.

Is there a function returning the absolute root ?

TIA

Andre