singleOrDefault method
Emits the single element of this Observable, or emits tooFew
if there
was no element, or emits tooMany
if there was more than 1 element.
Implementation
Observable<T> singleOrDefault({required T tooFew, required T tooMany}) =>
singleOrElse(
tooFew: constantFunction0(tooFew),
tooMany: constantFunction0(tooMany),
);