code: def incrementing_sleep(self, previous_attempt_number, delay_since_first_attempt_ms):
          
          result = self._wait_incrementing_start + (self._wait_incrementing_increment * (previous_attempt_number - 1))
          if result < 0:
              result = 0
          return result
docs: Sleep an incremental amount of time after each attempt, starting at
          wait_incrementing_start and incrementing by wait_incrementing_increment