anchor.diff:  	% Start the simulation timer
   	erlang:send_after(?INTERVAL, self(), simulate),
   
  -	{ok, State}.
  +	{ok, #state{}}.
   
   %% --------------------------------------------------------------------------------------------------------------------
   
   handle_call({add, Entity}, _From, State) ->
  -	NewState = add_entity(Entity, State),
  +	NewState = add_entity_internal(Entity, State),
   	% Notify all engine supervisors that we now own this entity.
   	pre_entity_engine_sup:cast_all({entity_added, Entity#entity.id, self()}),
       {reply, ok, NewState};
  
positive.code: 	erlang:send_after(?FULL_INTERVAL, self(), {full_update, EntityID}),
  
  	State#state {
  		entities = dict:append(EntityID, Entity, Entities)
  	}.
  
  
  
negative.code: %% --------------------------------------------------------------------------------------------------------------------
  
  init([]) ->
  	% Join the entity_engines process group.
  	pg2:create(entity_engines),
  	pg2:join(entity_engines, self()),
  