code: def delay_response_series(self):
          
          delays = []
          responses = []
          sum_responses = 0.
          for t in itertools.count(self.dt_response/2., self.dt_response):
              delays.append(t)
              response = self(t)
              responses.append(response)
              sum_responses += self.dt_response*response
              if (sum_responses > .9) and (response < self.smallest_response):
                  break
          return numpy.array(delays), numpy.array(responses)
docs: A tuple of two numpy arrays, which hold the time delays and the
          associated iuh values respectively.