code: def _time_string(self, value):
          
          if self.max_time < 60:
              return "%02d" % (value)
          elif self.max_time < 3600:
              mm = value // 60
              ss = value - mm * 60
              return "%02d:%02d" % (mm, ss)
          hh = value // 3600
          mm = (value - hh * 3600) // 60
          ss = (value - hh * 3600 - mm * 60)
          return "%02d:%02d:%02d" % (hh, mm, ss)
docs: Get a suitable time string
          ("ss", "mm:ss", "hh:mm:ss"),
          according to the maximum time.
  
          :param int value: the time value
          :rtype: string