code: public void dump(OutputStream ops) throws IOException {
          while (item.isLoaded) {
              item.dump(ops);
              // All content had been dumped, move to next
              if (!item.isLoaded)
                  item = item.next;
              // Else break the loop and waiting for next 'mark'
              else
                  break;
          }
          ops.flush();
      }
docs: 被 Dump 的节点将会通过标志表示可以再次加载
  
  @param ops
  输出流，如果为 null，则不会输出，直接改变标志
  @throws IOException