anchor.diff:  	erlang:send_after(?FULL_INTERVAL, self(), {full_update, EntityID}),
   
   	State#state {
  -		entities = dict:append(EntityID, Entity, Entities)
  +		entities = dict:store(EntityID, Entity, Entities)
   	}.
   
   
  
positive.code: 	% Start the simulation timer
  	erlang:send_after(?INTERVAL, self(), simulate),
  
  	{ok, State}.
  
  %% --------------------------------------------------------------------------------------------------------------------
  
  handle_call({add, Entity}, _From, State) ->
  	NewState = add_entity(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};
  
negative.code: %% --------------------------------------------------------------------------------------------------------------------
  
  init([]) ->
  	% Join the entity_engines process group.
  	pg2:create(entity_engines),
  	pg2:join(entity_engines, self()),
  