code: def list_topics(self, request):
          
          headers = {}
          params = {}
          if request.get_token() is not None:
              params['token'] = request.get_token()
          if request.get_line() is not None:
              params['line'] = request.get_line()
          params['type'] = 'topic'
          logstore = request.get_logstore()
          project = request.get_project()
          resource = "/logstores/" + logstore
          (resp, header) = self._send("GET", project, None, resource, params, headers)
  
          return ListTopicsResponse(resp, header)
docs: List all topics in a logstore.
          Unsuccessful opertaion will cause an LogException.
          
          :type request: ListTopicsRequest
          :param request: the ListTopics request parameters class.
          
          :return: ListTopicsResponse
          
          :raise: LogException