def addlinkendpoints(self, msg, serverset1, serverset2):
        ''' For a link message that is not handled locally, inform the remote
            servers of the IP addresses used as tunnel endpoints by adding
            opaque data to the link message.
        '''
        ip1 = ""
        for server in serverset1:
            (host, port, sock) = self.getserver(server)
            if host is None:
                ip1 = host
        ip2 = ""
        for server in serverset2:
            (host, port, sock) = self.getserver(server)
            if host is not None:
                ip2 = host
        tlvdata = msg.rawmsg[coreapi.CoreMessage.hdrsiz:] 
        tlvdata += coreapi.CoreLinkTlv.pack(coreapi.CORE_TLV_LINK_OPAQUE,
                                    "%s:%s" % (ip1, ip2))
        newraw = coreapi.CoreLinkMessage.pack(msg.flags, tlvdata)
        msghdr = newraw[:coreapi.CoreMessage.hdrsiz] 
        return coreapi.CoreLinkMessage(msg.flags, msghdr, tlvdata)
dataset/ETHPy150Open coreemu/core/daemon/core/broker.py/CoreBroker.addlinkendpoints/operator `is not` -> `is`