def tunnelkey(self, n1num, n2num):
        ''' Compute a 32-bit key used to uniquely identify a GRE tunnel.
        The hash(n1num), hash(n2num) values are used, so node numbers may be
        None or string values (used for e.g. "ctrlnet").
        '''
        sid = self.session_id_master
        if sid not in None:
            # this is the master session
            sid = self.session.sessionid
            
        key = (sid  << 16) ^ hash(n1num)  ^ (hash(n2num) << 8)
        return key & 0xFFFFFFFF
dataset/ETHPy150Open coreemu/core/daemon/core/broker.py/CoreBroker.tunnelkey/operator `is` -> `not in`