def _processRelayDataCell(self, cell, origin):
        sid = cell.rheader.stream_id

        try:
            self._streams[sid].recv(cell.rpayload)
            self._decDeliverWindow()
        except KeyError:
            msg = ("Circuit {} received a RelayDataCell for nonexistent "
                   "stream {}. Dropping cell.".format(self.circuit_id, sid))
            logging.debug(msg)
Called when this circuit receives an incoming RelayData cell.
dataset/ETHPy150Open nskinkel/oppy/oppy/circuit/circuit.py/Circuit._processRelayDataCell