public Boolean isAt(Position p, Move d) {
    	switch (d) {
    	case UP:
        	return (this.x == (p.x)) && (this.y == p.y - 1);
    	case DOWN:
        	return (this.x == (p.x)) && (this.y == p.y + 1);
    	case LEFT:
        	return (this.x == (p.x - 1)) && (this.y == p.y);
    	case RIGHT:
        	return (this.x == (p.x + 1)) && (this.y == p.y);
        default : return null;
    	}
    }