def METHOD_NAME(self, packet, item):
    limits_set = self._get_limits_set()
    # Values must be initialized with a 'DEFAULT' key
    if item.limits.values is None:
        if limits_set == "DEFAULT":
            item.limits.values = {"DEFAULT": []}
        else:
            raise self.parser.error(
                f"DEFAULT limits set must be defined for {packet.target_name} {packet.packet_name} {item.name} before setting limits set {limits_set}"
            )