     
     private final class Broadcaster {
         
-        internal typealias Object = WeakObject<_Observation>
+        internal typealias Object = WeakObject<PropertyObservation>
         
         private final var objects: [Object] = []
         

        )
        -> Observation {
            
            let observation = _Observation(observer: observer)
            
            objects.append(
                WeakObject(observation)


internal extension Property {
    
    private final class PropertyObservation: Observation {
        
        private final let observer: (ObservedChange) -> Void
        
