public static IDataflow <Either <TLeft, TRightOutput> > SelectManySafeAsync <TLeft, TRightInput, TRightOutput>( this IDataflow <Either <TLeft, TRightInput> > source, Func <TRightInput, Task <IEnumerable <Either <TLeft, TRightOutput> > > > selector) { return(source.SelectManyAsync(item => item.SelectManySafeAsync(selector))); }