code: def cmd_average_response_time(self):
          
          average = [
              line.time_wait_response
              for line in self._valid_lines
              if line.time_wait_response >= 0
          ]
  
          divisor = float(len(average))
          if divisor > 0:
              return sum(average) / float(len(average))
          return 0
docs: Returns the average response time of all, non aborted, requests.