anchor.diff:  terminate(_Reason, State) ->
   	ok.
   
  -handle_call({new, Type}, From, State) ->
  +handle_call({add, auto_increment}, From, State) ->
   	{Pid, Npcs} = State,
   	MyBucket = <<"npc">>,
   	Id = rutil:auto_increment("npc"),
  -	BinK = erlang:term_to_binary(Id),
  -	Obj1 = riakc_obj:new(MyBucket, BinK, "hoge"),
  +	BinId = erlang:term_to_binary(Id),
  +	Obj1 = riakc_obj:new(MyBucket, BinId, "default"),
   	riakc_pb_socket:put(Pid, Obj1),
   	NewState = {Pid, [Id | Npcs]},
   	{reply, {ok, Id}, NewState};
   
  -handle_call({add, Id, V}, From, State) ->
  +handle_call({add, Id}, From, State) ->
   	{Pid, Npcs} = State,
   	MyBucket = <<"npc">>,
   	BinId = erlang:term_to_binary(Id),
  -	Obj1 = riakc_obj:new(MyBucket, BinId, V),
  -	riakc_pb_socket:put(Pid, Obj1),
  -	{reply, ok, State};
  +	{ok, Fetched} = riakc_pb_socket:get(Pid, MyBucket, BinId),	%% check if key existing "BinId"
  +	NewState = {Pid, [Id | Npcs]},
  +	{reply, ok, NewState};
  +
  +handle_call({is_on, Id}, From, State) ->
  +	{Pid, Npcs} = State,
  +	{reply, {ok, lists:member(Id , Npcs)}, State};
   
   handle_call({lookup, Id}, From, State) ->
   	{Pid, Npcs} = State,
  
positive.code: %% APIs
  %%
  
  new() ->
  	Reply = gen_server:call(?MODULE, {new, 0}).
  
  new(Type) ->
  	Reply = gen_server:call(?MODULE, {new, Type}).
  
  add(K, V) ->
  	Reply = gen_server:call(?MODULE, {add, K, V}).
  
  lookup(K) ->
  	Reply = gen_server:call(?MODULE, {lookup, K}).
  
  remove(K) ->
  	Reply = gen_server:call(?MODULE, {remove, K}).
  
  run() ->
  	Reply = gen_server:call(?MODULE, {run, 1000}).
  
negative.code: 
  handle_call({remove, Id}, From, State) ->
  	{Pid, Npcs} = State,
  	NewState = {Pid, lists:delete(Id , Npcs)},
  	{reply, {ok, Id}, NewState};
  
  