public void increment(int by) {
		// if given value is negative, we have to decrement
		if (by < 0) {
			decrement(Math.abs(by));
			return;
		}

		// check if we would overflow
		int space_up = max - value;
		if (by > space_up) {
			// we simply use max
			value = max;
		} else {
			// no overflowing, this is easy
			value += by;
		}
	}