code: public BaseWindowedBolt<T> countWindow(long size, long slide) {
          ensurePositiveTime(size, slide);
          ensureSizeGreaterThanSlide(size, slide);
  
          setSizeAndSlide(size, slide);
          this.windowAssigner = SlidingCountWindows.create(size, slide);
          return this;
      }
docs: define a sliding count window
  
  @param size  count size
  @param slide slide size