anchor.diff:              %State1 = locally_disable_lease(State, NewLease),
               {ok, State, SlideOp};
           {split, fail, _Lease} ->
  -            %% log:log("prepare_send_delta2: split failed~n", []),
  +            log:log("prepare_send_delta2: split failed~n", []),
               {abort, {protocol_error, Msg}, State, SlideOp}
       end.
   
  
positive.code: -spec prepare_send_delta1(State::dht_node_state:state(), SlideOp::slide_op:slide_op(),
                            ReplyPid::comm:erl_local_pid())
          -> {ok, dht_node_state:state(), slide_op:slide_op()} |
             {abort, Reason::unkown_lease, State::dht_node_state:state(), SlideOp1::slide_op:slide_op()}.
  prepare_send_delta1(State, OldSlideOp, ReplyPid) ->
      % start to split own range
      %log:log("prepare_send_delta1 ~p~n", [slide_op:get_type(OldSlideOp)]),
  
negative.code:             Interval = slide_op:get_interval(OldSlideOp),
              case Interval =:= l_on_cseq:get_range(Lease) of
                  false ->
                      case intervals:in(Id, Interval) of
                          true ->
                                                  % ->
                              log:log("unsupported slide direction in prepare_send_delta1~n"),
                              log:log("~p in ~p~n == false", [Id, Interval]),
                              log:log("~p~n", [Lease]),
                              {abort, {protocol_error, unsupported_slide_direction}, State, OldSlideOp};
                          false ->
                                                  % <-
                              {R1, R2} =  {Interval, intervals:minus(l_on_cseq:get_range(Lease), Interval)},
                              NewOwner = node:pidX(slide_op:get_node(OldSlideOp)),
                              l_on_cseq:lease_split_and_change_owner(Lease, R1, R2, NewOwner, ReplyPid),
                              {ok, State, OldSlideOp}
                      end;
                  true ->
                      log:log("only change owner instead of split and change owner", []),
                      %% @todo
  