class SlidingWindowCounter {

    public long get(int slots) {
        checkArgument(slots <= windowSlots,
                      "Requested window must be less than the total window slots");

        long sum = 0;

        for (int i = 0; i < slots; i++) {
            int currentIndex = headSlot - i;
            if (currentIndex < 0) {
                currentIndex = counters.size() + currentIndex;
            }
            sum += counters.get(currentIndex).get();
        }

        return sum;
    }

    public  SlidingWindowCounter(int windowSlots);

}