anchor.diff:  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   -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()}.
  +        -> {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)]),
  
positive.code:                         NextOpMsg, EmbeddedMsg::{continue})
          -> {ok, dht_node_state:state(), slide_op:slide_op(), NextOpMsg}
          when is_subtype(NextOpMsg, dht_node_move:next_op_msg()).
  finish_delta_ack2(State, SlideOp, NextOpMsg, _Msg) ->
      % notify neighbor on successful handover
      %log:log("finish_delta_ack2 ~p~n", [_Msg]),
      % notify succ
  
negative.code:             {ok, State1, SlideOp, NextOpMsg};
          error ->
              log:log("error in finish_delta_ack2"),
              {abort, {protocol_error, Msg}, State, SlideOp}
      end.
  
  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  