anchor.diff:  	#state{by_id = ByIdDict, by_map = ByMapDict}.
   
   %% move in same map.
  -update_all_state(OldValue, NewValue, State)
  -	when is_record(OldValue, info),
  -		is_record(NewValue, info),
  -		OldValue#info.map == NewValue#info.map ->
  +	%%when is_record(OldValue, info),
  +	%%	is_record(NewValue, info),
  +	%%	OldValue#info.map == NewValue#info.map ->
  +update_all_state(OldValue, NewValue, State) ->
   
   	#state{by_id = ByIdDict, by_map = ByMapDict} = State,
   	Id = NewValue#info.id,
  
positive.code: %% move to another map.
  update_all_state(OldValue, NewValue, State) ->
  	State.
  
  get_map_by_id(Id, State) ->
  	case dict:find(Id, State#state.by_id) of
  
negative.code: 	Info2_1_1 = #info{id=2, map=m1, x=101, y=101},
  	Info2_2_2 = #info{id=2, map=m2, x=102, y=101},
  	set_info(1, Info1_1_1),
  	io:format("~p~n", [get_all_neighbors(1)]),
  	set_info(1, Info1_1_2),
  	io:format("~p~n", [get_all_neighbors(1)]),
  	set_info(2, Info2_1_1),
  	io:format("~p~n", [get_all_neighbors(1)]).
  
  get_info(Id) ->
  	{ok, V} = gen_server:call(?MODULE, {get_info, Id}) ,
  