cosumer.dart

ValueBloc valueBloc = BlocProvider.getBloc<ValueBloc>();

...

StreamBuilder<String>(
  stream: valueBloc.valueStringOut,
  initialData: "",
  builder: (context, snapshot) {
    return Text(snapshot.data,
      style: TextStyle(
        color: Colors.white,
        fontSize: 24,
        fontWeight: FontWeight.bold,
      ),
    );
  },
),

...

StreamBuilder<double>(
  stream: valueBloc.valueOut,
  initialData: 0
  builder: (context, snapshot) {
    return Slider(
    activeColor: Colors.white,
    inactiveColor: Colors.white,
    min: 0.0,
    max: 1.0,
    onChanged: valueBloc.onChangeValue,
    value: snapshot.data);
  },
),