'Helper for ``_index()``'

def _index_helper(self, xmltree, fileid):

    vnclass = xmltree.get(u'ID')
    self._class_to_fileid[vnclass] = fileid
    self._shortid_to_longid[self.shortid(vnclass)] = vnclass
    for member in xmltree.findall(u'MEMBERS/MEMBER'):
        self._lemma_to_class[member.get(u'name')].append(vnclass)
        for wn in member.get(u'wn', u'').split():
            self._wordnet_to_class[wn].append(vnclass)
    for subclass in xmltree.findall(u'SUBCLASSES/VNSUBCLASS'):
        self._index_helper(subclass, fileid)
