multicast method
Multicast observable make multiple observers share single source subscription.
Subject is used to forward source item to downward observers.
Shared subscription keep alive using ARC (auto reference count) of observers.
Implementation
Observable<T> multicast({
Subject<T> Function()? createSubject,
}) {
return ObservableMulticast<T>(
createSubject: createSubject,
source: this,
);
}