docs: def plain_payload(self):
          """obtain stats payload in plaintext format"""
          tstamp = int(time.time())
          payload = []
          for item in self.counters:
              payload.append('%s.%s%s %s %s\n' % (self.rate_prefix,
                                                  item,
                                                  self.rate_suffix,
                                                  self.counters[item] /
                                                  self.flush_interval,
                                                  tstamp))
              payload.append('%s.%s%s %s %s\n' % (self.count_prefix,
                                                  item,
                                                  self.count_suffix,
                                                  self.counters[item],
                                                  tstamp))
              self.counters[item] = 0
  
          for key in self.timers:
              if len(self.timers[key]) > 0:
                  self.process_timer_key(key, tstamp, payload)
                  self.timers[key] = []
  
          for key in self.gauges:
              payload.append("%s.%s %d %d\n" % (self.gauge_prefix, key,
                                                self.gauges[key], tstamp))
              self.gauges[key] = 0
  
          if self.debug:
              print payload
  
          if payload:
              return "".join(payload)
          else:
              return None