code: def namespace(self, prefix=None):
          
          e = self.__deref()
          if e is not None:
              return e.namespace(prefix)
          return super(Element, self).namespace()
docs: Get this schema element's target namespace.
  
          In case of reference elements, the target namespace is defined by the
          referenced and not the referencing element node.
  
          @param prefix: The default prefix.
          @type prefix: str
          @return: The schema element's target namespace
          @rtype: (I{prefix},I{URI})