public static IRxVal <B> flatMap <A, B>(this IRxVal <A> rx, Fn <A, IRxVal <B> > mapper) =>
RxVal.a(
() => mapper(rx.value).value,
ObservableOpImpls.flatMap(rx, mapper)
);
/**
* Maps events coming from this observable and emits events from returned futures.
*
* Does not emit value if future completes after observable is finished.
**/
public static IObservable <B> flatMap <A, B>(
this IObservable <A> o, Fn <A, Future <B> > mapper
) => Observable.a(ObservableOpImpls.flatMap(o, mapper));