@class NSString; @interface NSObservationTransformer : NSObservationSource <NSObserver> @property (readonly) unsigned long long hash; @property (readonly) Class superclass; @property (readonly, copy) NSString *description; @property (readonly, copy) NSString *debugDescription; + (id)mapErrorsWithBlock:(id /* block */)a0; + (id)mapValuesWithBlock:(id /* block */)a0; @end