code: public void toggleExpandable(int position) {
          Item item = mFastAdapter.getItem(position);
          if (item instanceof IExpandable && ((IExpandable) item).isExpanded()) {
              collapse(position);
          } else {
              expand(position);
          }
      }
docs: toggles the expanded state of the given expandable item at the given position
  
  @param position the global position