docs: public long getAndSet(T item, long value) {
          MutableLong entry = map.get(item);
  
          if (entry == null) {
              entry = MutableLong.valueOf(value);
              map.put(item, entry);
              total += value;
              return 0;
          }
  
          long oldValue = entry.value;
          total = total - oldValue + value;
          entry.value = value;
          return oldValue;
      }