anchor.diff:  
   -export([start_link/0]).
   -export([init/1, handle_call/3, handle_cast/2]).
  +
  +-export([test/0]).
   
   -record(info, {id, map, x, y}).
   -record(state, {by_id, by_map}).
  
positive.code: %%
  
  test() ->
  	Info1_1_1 = #info{id=1, map=1, x=1, y=1},
  	Info1_1_2 = #info{id=1, map=1, x=2, y=2},
  	Info1_2_1 = #info{id=1, map=2, x=1, y=1},
  	Info2_1_1 = #info{id=2, map=1, x=1, y=1},
  	Info2_2_2 = #info{id=2, map=2, x=2, y=1},
  	set_info(1, Info1_1_1).
  
  get_info(Id) ->
  	gen_server:call(?MODULE, {get_info, Id}) .
  
  get_info(Id, Default) ->
  	{ok, V} = gen_server:call(?MODULE, {get_info, Id}) ,
  
negative.code: 
  handle_call({get_all_neighbors, Id}, _From, State) ->
  	MapId = get_map_by_id(Id, State),
  	Result = get_info_list_by_map(MapId, State),
  	{reply, {ok, Result}, State};
  
  handle_call({get_info, Id}, _From, State) ->
  