def getBytes(self):
            fmt = "!HB" if self.link_version <= 3 else "!IB"
            return struct.pack(fmt, self.circ_id, self.cmd)
Encrypts the underlying socket with the information given by
dataset/ETHPy150Open nskinkel/oppy/oppy/cell/fixedlen.py/FixedLenCell.Header.getBytes--crossover with--dataset/ETHPy150Open slimta/python-slimta/slimta/smtp/client.py/Client.encrypt