code: def tick(self, unit_value):
      
      total_secs = round(time.time() - self.__prev_tick)
      if total_secs >= 1:
        self.__unit_per_sec = unit_value / total_secs - self.__unit_per_sec_prev
        self.__unit_per_sec_prev = unit_value
        self.__prev_tick = time.time()
docs: :type unit_value int