anchor.diff:  on({l_on_cseq, merge_reply_step4, L1, ReplyTo,
       {qwrite_deny, _ReqId, Round, L2, Reason}}, State) ->
       % @todo if success update lease in State
  -    ct:pal("merge step4 failed~n~w~n~w~n~w~n", [Reason, L1, L2]),
  +    log:pal("merge step4 failed~n~w~n~w~n~w~n", [Reason, L1, L2]),
       % retry?
       case Reason of
           unexpected_timeout ->
  
positive.code: on({l_on_cseq, merge_reply_step1, L2, _ReplyTo,
      {qwrite_deny, _ReqId, Round, L1, Reason}}, State) ->
      % @todo if success update lease in State
      ct:pal("merge step1 failed~n~w~n~w~n~w~n", [Reason, L1, L2]),
      % retry?
      %State;
      lease_list:update_next_round(l_on_cseq:get_id(L1), Round, State);
  
negative.code:     fun (prbr_bottom, _WriteFilter, _Next) ->
              {false, lease_does_not_exist};
          (Current, _WriteFilter, _Next) when Current =:= New ->
              log:pal("re-write in CC:~n~w~n~w~n~w~n~w~n~w~n", [Current, _Next, Old, New, Writer]),
              {true, null};
          (#lease{id = Id0}, _, _)    when Id0 =/= OldId->
              {false, unexpected_id};
  