code: def mktns(self):
          
          tns = [None, self.root.get('targetNamespace')]
          if tns[1] is not None:
              tns[0] = self.root.findPrefix(tns[1])
          return tuple(tns)
docs: Make the schema's target namespace.
          @return: The namespace representation of the schema's
              targetNamespace value.
          @rtype: (prefix, uri)