 
     /**
     Constructs a new `NotificationObserver` instance and immediately registers to begin observing the specified `notification`.
-    To unregister this observer and end listening for notifications, dealloc the object by setting it to `nil`.
+    
+    - warning: To unregister this observer and end listening for notifications, dealloc the object by setting it to `nil`.
 
     - parameter notification: The notification for which to register the observer.
     - parameter queue:        The operation queue to which `handler` should be added.


    /**
    Constructs a new `NotificationObserver` instance and immediately registers to begin observing the specified `notification`.
    To unregister this observer and end listening for notifications, dealloc the object by setting it to `nil`.

    - parameter notification: The notification for which to register the observer.
    - parameter queue:        The operation queue to which `handler` should be added.

/**
An instance of `NotificationObserver` is responsible for observing notifications.

- note: When an observer is initialized, it will immediately begin listening for its specified notification
by registering with the specified notification center.
*/
public final class NotificationObserver <V, S: AnyObject> {
