code: def isoformat(self):
          
          s = _format_time(self._hour, self._minute, self._second,
                           self._microsecond)
          tz = self._tzstr()
          if tz:
              s += tz
          return s
docs: Return the time formatted according to ISO.
  
          This is 'HH:MM:SS.mmmmmm+zz:zz', or 'HH:MM:SS+zz:zz' if
          self.microsecond == 0.