[Zope-CMF] How to get the main parent from a discussion item?

[Ausum]

I'm trying to provide a link to the main parent (discussable documents,
news, etc ) within all the discussions items resulting from it, no matter
its nesting level.
I've been trying to get into the aboveinThread.py script and the
parentsInThread method trying to figure out a solution but I got stuck
again.
Would you please tell me what I'm doing wrong here?:

def the_parent(self)
        current = self
        while parent.meta_type=self.meta_type:
            parent = current.inReplyTo()
            current = parent
        return parent

What would it be the DTML way?

Thanks in advance,


Ausum