@class NSString; @interface NSObservationSink : NSObject <NSObserver> @property (readonly) unsigned long long hash; @property (readonly) Class superclass; @property (readonly, copy) NSString *description; @property (readonly, copy) NSString *debugDescription; + (id)handleErrorsWithBlock:(id /* block */)a0; + (id)handleValuesWithBlock:(id /* block */)a0; @end