code: def get_basic_sort_link(self, request, field):
          query_string = self.get_querystring()
          sort_string = self.get_next_sort_string(field)
          if sort_string:
              sort_link = request.path + '?' + sort_string
              if query_string:
                  sort_link += '&' + query_string
          else:
              sort_link = request.path
              if query_string:
                  sort_link += '?' + query_string
          return sort_link