code: public void addHeuristicCpuCost(double cost) {
  		if (cost <= 0) {
  			throw new IllegalArgumentException("Heuristic costs must be positive.");
  		}
  		this.heuristicCpuCost += cost;
  		// check for overflow
  		if (this.heuristicCpuCost < 0) {
  			this.heuristicCpuCost = Double.MAX_VALUE;
  		}
  	}
docs: Adds the given heuristic CPU cost to the current heuristic CPU cost for this Costs object.
  
  @param cost The heuristic CPU cost to add.