FuseToObservable

Type Parameters:

T - the value type

All Known Implementing Classes:

ObservableAllSingle, ObservableAnySingle, ObservableCollectSingle, ObservableCollectWithCollectorSingle, ObservableCountSingle, ObservableElementAtMaybe, ObservableElementAtSingle, ObservableFlatMapCompletableCompletable, ObservableIgnoreElementsCompletable, ObservableSequenceEqualSingle, ObservableToListSingle
```
public interface FuseToObservable<@NonNull T>
```
Interface indicating a operator implementation can be macro-fused back to Observable in case the operator goes from Observable to some other reactive type and then the sequence calls for toObservable again:
```
 
 Single<Integer> single = Observable.range(1, 10).reduce((a, b) -> a + b);
 Observable<Integer> observable = single.toObservable();
 
 
```
The Single.toObservable() will check for this interface and call the fuseToObservable() to return an Observable which could be the Observable-specific implementation of reduce(BiFunction).
This causes a slight overhead in assembly time (1 instanceof check, 1 operator allocation and 1 dropped operator) but does not incur the conversion overhead at runtime.

- Method Summary
  
  All Methods Instance Methods Abstract Methods
  Modifier and Type Method Description
  
  @NonNull Observable<T> fuseToObservable()
  Returns a (direct) Observable for the operator.

- Method Detail
  - fuseToObservable
```
@NonNull
@NonNull Observable<T> fuseToObservable()
```
    Returns a (direct) Observable for the operator.
    The implementation should handle the necessary RxJavaPlugins wrapping.
    
    Returns:
    
    the Observable instance