code: def get_threads(self, querystring, sort='newest_first', exclude_tags=None):
          assert sort in self._sort_orders
          q = self.query(querystring)
          q.set_sort(self._sort_orders[sort])
          if exclude_tags:
              for tag in exclude_tags:
                  q.exclude_tag(tag)
          return self.async_(q.search_threads, (lambda a: a.get_thread_id()))