addTo method Null safety
- EventSink<
T> sink 
override
    Adds this result to an EventSink.
Calls the sink's add or addError method as appropriate.
Implementation
@override
void addTo(EventSink<T> sink) {
  sink.add(value);
}
Adds this result to an EventSink.
Calls the sink's add or addError method as appropriate.
@override
void addTo(EventSink<T> sink) {
  sink.add(value);
}