   let notificationCenter: NotificationCenter
   private let handler: Handler
   private var tokens = [NSObjectProtocol]()
+
+   // MARK: - Initializers
 
   public init(kind: Kind, event: ObservedEvent, notificationCenter: NotificationCenter = .default, notificationQueue: OperationQueue? = nil, handler: @escaping Handler) {
     self.kind = kind

      }
    }
  }

  let kind: Kind
  let event: ObservedEvent


import CoreData

public extension ManagedObjectContextChangesObserver {
  enum Kind {
    case all(matching: (NSManagedObjectContext) -> Bool)
    case one(context: NSManagedObjectContext)

