docs: public int forEach(final ToIntFunction<SelectionKey> function)
      {
          int handledFrames = 0;
          final SelectionKey[] keys = this.keys;
  
          for (int i = size - 1; i >= 0; i--)
          {
              handledFrames += function.applyAsInt(keys[i]);
          }
  
          size = 0;
  
          return handledFrames;
      }