private String stackGraph(int i) {
        switch (i) {
        case 0:
            return " ____";
        case 1:
            return "/ ___|   ";
        case 2:
            return "\\___ \\   ";
        case 3:
            return " ___) |  ";
        case 4:
            return "|____/   ";
        }
        return null;
    }