private double pathCostEstimate(Location start, Location goal, Agent agent) {
		if (agent == null) { // default agent
			int dx = Math.abs(goal.x - start.x);
			int dy = Math.abs(goal.y - start.y);
			double diff = (double) Math.abs(dx - dy);

			return typicalCost * (dx + dy);
		} else {
			return 1;
		}
	}