code: def fmt_second(time_total):
      
  
      def _ck(t):
          return t < 10 and "0%s" % t or t
  
      times = int(time_total)
      h = times / 3600
      m = times % 3600 / 60
      s = times % 3600 % 60
      return "%s:%s:%s" % (_ck(h), _ck(m), _ck(s))
docs: >>> fmt_second(100)
      '00:01:40'