anchor.diff:  add() ->
   	Reply = gen_server:call(?MODULE, {add, auto_increment}).
   
  -add(Id) ->
  -	Reply = gen_server:call(?MODULE, {add, Id}).
  +remove(Id) ->
  +	Reply = gen_server:call(?MODULE, {remove, Id}).
  +
  +online(Id) ->
  +	Reply = gen_server:call(?MODULE, {online, Id}).
  +
  +offline(Id) ->
  +	Reply = gen_server:call(?MODULE, {offline, Id}).
   
   is_on(Id) ->
   	Reply = gen_server:call(?MODULE, {is_on, Id}).
  
positive.code: lookup(Id) ->
  	Reply = gen_server:call(?MODULE, {lookup, Id}).
  
  remove(Id) ->
  	Reply = gen_server:call(?MODULE, {remove, Id}).
  
  run() ->
  	Reply = gen_server:call(?MODULE, {run, 1000}).
  
  run(IntervalMSec) ->
  	Reply = gen_server:call(?MODULE, {run, IntervalMSec}).
  
  %%
  %% Behaviors
  
negative.code: 	MyBucket = <<"npc">>,
  	Id = rutil:auto_increment("npc"),
  	BinId = erlang:term_to_binary(Id),
  	NewNpc = get_new_npc(),
  	Obj1 = riakc_obj:new(MyBucket, BinId, NewNpc),
  	riakc_pb_socket:put(Pid, Obj1),
  	NewState = {Pid, [Id | Npcs]},
  	{reply, {ok, Id}, NewState};
  
  handle_call({remove, Id}, From, State) ->
  	{Pid, Npcs} = State,
  	NewState = {Pid, lists:delete(Id , Npcs)},
  	MyBucket = <<"npc">>,
  	BinId = erlang:term_to_binary(Id),
  	riakc_pb_socket:delete(Pid, MyBucket, BinId),
  	{reply, {ok, Id}, NewState};
  
  handle_call({online, Id}, From, State) ->
  	{Pid, Npcs} = State,
  	MyBucket = <<"npc">>,
  	BinId = erlang:term_to_binary(Id),
  	{ok, Fetched} = riakc_pb_socket:get(Pid, MyBucket, BinId),	%% check if key existing "BinId"
  	NewState = {Pid, [Id | Npcs]},
  	{reply, ok, NewState};
  
  handle_call({offline, Id}, From, State) ->
  	{Pid, Npcs} = State,
  	NewState = {Pid, lists:delete(Id , Npcs)},
  	{reply, {ok, Id}, NewState};
  
  handle_call({is_on, Id}, From, State) ->
  	{Pid, Npcs} = State,
  