code: public AStarCostComputer<? super ST, ? super PT> setCostComputer(AStarCostComputer<? super ST, ? super PT> costComputer) {
  		final AStarCostComputer<? super ST, ? super PT> old = this.costComputer;
  		this.costComputer = costComputer;
  		return old;
  	}
docs: Set the tool that permits to compute the costs of the nodes and the edges.
  
  @param costComputer is the object that permits to compute the costs.
  @return the old cost computer.