code: public ViewHolder findViewHolderForItemId(long id) {
          final int childCount = getChildCount();
          for (int i = 0; i < childCount; i++) {
              final ViewHolder holder = getChildViewHolderInt(getChildAt(i));
              if (holder != null && holder.getItemId() == id) {
                  return holder;
              }
          }
          return mRecycler.findViewHolderForItemId(id);
      }
docs: Return the ViewHolder for the item with the given id. The RecyclerView must
  use an Adapter with {@link com.twotoasters.android.support.v7.widget.RecyclerView.Adapter#setHasStableIds(boolean) stableIds} to
  return a non-null value.
  
  @param id The id for the requested item
  @return The ViewHolder with the given <code>id</code>, of null if there
  is no such item.