# listenTo method Null safety

1. @override

StreamSubscription<ListedItemModel> listenTo(

1. String documentId,
2. ListedItemChanged changed,
3. {ListedItemErrorHandler? errorHandler}

)
override

## Implementation

    @override
    StreamSubscription<ListedItemModel> listenTo(
        String documentId, ListedItemChanged changed,
        {ListedItemErrorHandler? errorHandler}) {
      throw UnimplementedError();
    }