code: def skip(self, attr):
          
          ns = attr.namespace()
          skip = (
              Namespace.xmlns[1],
              'http://schemas.xmlsoap.org/soap/encoding/',
              'http://schemas.xmlsoap.org/soap/envelope/',
              'http://www.w3.org/2003/05/soap-envelope',
          )
          return ( Namespace.xs(ns) or ns[1] in skip )
docs: Get whether to skip (filter-out) the specified attribute.
          @param attr: An attribute.
          @type attr: I{Attribute}
          @return: True if should be skipped.
          @rtype: bool