Determine whether an attribute is of type ID. In case we
          have DTD(s) then this is done if DTD loading has been
          requested. In the case of HTML documents parsed with the
           HTML parser, then ID detection is done systematically.

def isID(self, doc, attr):
        """Determine whether an attribute is of type ID. In case we
          have DTD(s) then this is done if DTD loading has been
          requested. In the case of HTML documents parsed with the
           HTML parser, then ID detection is done systematically. """
        if doc is None: doc__o = None
        else: doc__o = doc._o
        if attr is None: attr__o = None
        else: attr__o = attr._o
        ret = libxml2mod.xmlIsID(doc__o, self._o, attr__o)
        return ret