docs: def xml_parser(self, scode, *args):
          """
          args[0]: xpath
  
          args[1]: text / html / xml
          """
          allow_method = ('text', 'html', 'xml')
          xpath_string, method = args
          assert method in allow_method, 'method allow: %s' % allow_method
          result = self.ensure_list(
              self._fromstring(scode,
                               parser=self._xml_parser).xpath(xpath_string))
          result = [
              self._tostring(
                  item, method=method, with_tail=0, encoding='unicode')
              for item in result
          ]
          return result