public int current() {
        return number;
    }

    public int next() {
        if (number < BOUND) {
            number++;

            serve();
        } else {
            begin();
        }

        return number;
    }

    public int previous() {
        if (number > 1) {
            number--;

            serve();
        } else {
            end();
        }

        return number;
    }

    public int begin() {
        number = 1;

        serve();

        return number;
    }

    public int end() {
        number = BOUND;

        serve();

        return number;
    }