anchor.diff:  add_target_resource_type(Type) ->
       gen_server:cast(?SERVER, {add_target_resource_type, Type}).
   
  -add_local_resource(Type, Instance) ->
  -    gen_server:cast(?SERVER, {add_local_resource, {Type, Instance}}).
  +add_local_resource(Type, Resource) ->
  +    gen_server:cast(?SERVER, {add_local_resource, {Type, Resource}}).
   
   fetch_resources(Type) ->
       gen_server:call(?SERVER, {fetch_resources, Type}).
  
positive.code:          add_local_resource/2,
           fetch_resources/1,
           trade_resources/0
  	]).
  
  -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
           terminate/2, code_change/3]).
  
negative.code:             dict:store(Type, [Resource], Dict)
      end.
  
  filter_remote_resources_by_target_types(Types, Resources) ->
      Fun =
          fun(Type, Acc) ->
              case dict:find(Type, Resources) of
                  {ok, List} ->
                      [{Type, Resource} || Resource <- List] ++ Acc;
                  error ->
                      Acc
              end
  