code: def isRef(self, elem, attr):
          
          if elem is None: elem__o = None
          else: elem__o = elem._o
          if attr is None: attr__o = None
          else: attr__o = attr._o
          ret = libxml2mod.xmlIsRef(self._o, elem__o, attr__o)
          return ret
docs: Determine whether an attribute is of type Ref. In case we
            have DTD(s) then this is simple, otherwise we use an
             heuristic: name Ref (upper or lowercase).