asStream method
Creates a Stream containing the result of this future.
The stream will produce single data or error event containing the completion result of this future, and then it will close with a done event.
If the future never completes, the stream will not produce any events.
Implementation
@override
ObservableStream<T> asStream() => ObservableStream._(
_context, _future.asStream(), value, false, '${name}_asStream', null);