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

        try:
            self._streams[sid].streamConnected()
        except KeyError:
            msg = ("Circuit {} received a RelayConnectedCell for nonexistent "
                   "stream {}. Dropping cell.".format(self.circuit_id, sid))
            logging.debug(msg)
            return

        msg = ("Circuit {} received a RelayConnectedCell for stream {}"
               .format(self.circuit_id, sid))
        logging.debug(msg)
Called when this circuit receives a RelayConnectedCell.
dataset/ETHPy150Open nskinkel/oppy/oppy/circuit/circuit.py/Circuit._processRelayConnectedCell