def serialize(self, buf, offset):
        n, value, mask = ofproto.oxm_from_user(self.key, self.value)
        len_ = ofproto.oxm_serialize(n, value, mask, buf, offset + 4)
        self.len = utils.round_up(4 + len_, 8)
        msg_pack_into('!HH', buf, offset, self.type, self.len)
        pad_len = self.len - (4 + len_)
        msg_pack_into(pad_len % "%dx", buf, offset + 4 + len_)
dataset/ETHPy150Open osrg/ryu/ryu/ofproto/ofproto_v1_4_parser.py/OFPActionSetField.serialize/swapped operands of `%`