code: def append(self, data, start):
          
          if self._limit is not None and self._limit > 0:
              if self._start is None:
                  self._start = start
              if start - self._start > self.reset_rate:
                  self._sum -= round((start - self._start) * self._limit)
                  self._start = start
              self._sum += len(data)
docs: Count `data` for throttle
  
          :param data: bytes of data for count
          :type data: :py:class:`bytes`
  
          :param start: start of read/write time from
              :py:meth:`asyncio.BaseEventLoop.time`
          :type start: :py:class:`float`