code: public AStarHeuristic<? super PT> setEvaluationHeuristic(AStarHeuristic<? super PT> heuristic) {
  		final AStarHeuristic<? super PT> old = this.heuristic;
  		this.heuristic = heuristic;
  		return old;
  	}
docs: Set the evaluation heuristic used by the A* algorithm.
  
  @param heuristic is the evaluation heuristic.
  @return the old heurisstic.