Widget build(BuildContext context) {
  return Builder(builder: (context) {
    final dirSizesBloc = context.watch<DirSizesBloc>();

    if (dirSizesBloc.state.sizes
        .containsKey(dir.id)) {
      final size =
      dirSizesBloc.state.sizes[dir.id];

      return StreamBuilder(
          stream: size, builder: (context, snapshot) {
        if(snapshot.hasData && (snapshot.data as DirSize).isCalculated) {
          return Text((snapshot.data as DirSize).size);
        }

        return Loading();
      });
    }

    return Loading();
  });
}