code: def skip(self, ns):
          
          return ns in (None, Namespace.default, Namespace.xsdns, Namespace.xsins, Namespace.xmlns)
docs: Get whether the I{ns} is to B{not} be normalized.
          @param ns: A namespace.
          @type ns: (p,u)
          @return: True if to be skipped.
          @rtype: boolean