code: public void doLoad(final Card card) {
          if (mAsyncLoader == null) {
              return;
          }
          if (!card.loading && !card.loaded) {
              card.loading = true;
              mAsyncLoader.loadData(card, new AsyncLoader.LoadedCallback() {
                  @Override
                  public void finish() {
                      card.loading = false;
                      card.loaded = true;
                  }
  
                  @Override
                  public void finish(List<BaseCell> cells) {
                      finish();
                      card.addCells(cells);
                      card.notifyDataChange();
                  }
  
                  public void fail(boolean loaded) {
                      card.loading = false;
                      card.loaded = loaded;
                  }
              });
          }
      }
docs: start load data for a card, usually called by {@link TangramEngine}
  @param card the card need async loading data