Returns the value of the
indexth data event of this stream.
Stops listening to this stream after the
indexth data event has been
Internally the method cancels its subscription after these elements. This means that single-subscription (non-broadcast) streams are closed and cannot be reused after a call to this method.
If an error event occurs before the value is found, the future completes with this error.
If a done event occurs before the value is found, the future completes
@override AsObservableFuture<T> elementAt(int index) => AsObservableFuture<T>(_stream.elementAt(index));