code: def date_time_string(self, timestamp=None):
          
          if timestamp is None:
              timestamp = time.time()
          year, month, day, hh, mm, ss, wd, y, z = time.gmtime(timestamp)
          s = "%s, %02d %3s %4d %02d:%02d:%02d GMT" % (
                  self.weekdayname[wd],
                  day, self.monthname[month], year,
                  hh, mm, ss)
          return s
docs: Return the current date and time formatted for a message header.