@classmethod
    def parser(cls, buf):
        (nxt, size, spi, seq) = struct.unpack_from(cls._PACK_STR, buf)
        form = "%ds" % (cls._MIN_LEN - cls._get_size(size))
        (data, ) = struct.unpack_from(form, buf, cls._MIN_LEN)
        return cls(nxt, size, spi, seq, data)
dataset/ETHPy150Open osrg/ryu/ryu/lib/packet/ipv6.py/auth.parser/swapped operands of `-`