libxml2 and node identity

I've been trying to find information with how to figure out node 
identity in libxml2 - but I'm at a loss.  I can't seem to find what I'm 
looking for on the xmlsoft.org site and google doesn't seem to help at 
all with the following query:

http://www.google.com/search?q=libxml2+node+identity

Here's a snippet to show the problem:

 >>> import libxml2>>> doc = libxml2.newDoc('1.0')>>> root = doc.newChild(None, 'root', None)>>> print root, doc.children
<xmlNode (root) object at 0x419c60> <xmlNode (root) object at 0x4710d0>
 >>> print root._o, doc.children._o
<PyCObject object at 0x221d0> <PyCObject object at 0x22170>

What I'd _like_ to do is to be able to check that two nodes are actually 
identical.  The Python wrappers as well as the PyCObject references 
don't seem to match up.  I also can't seem to find any way to do 
something like "node.isSameNode(otherNode)"

Help!