     public func unwatch(target: AnyObject) {
         
         ObservingUnwatch(self, target)
+    }
+    
+    public func equals(rhs: Element) -> Bool {
+
+        if let oldValue = self.value {
+            return self.equatable(newValue: rhs, oldValue: oldValue)
+        }
+        return false
     }
     
     func trigger(e: Event) {

        ObservingUnwatch(self, target)
    }
    
    func trigger(e: Event) {
        
        ObservingTrigger(self, e)

    public func unwatch(target: AnyObject) {
        
        ObservingUnwatch(self, target)
    }
    
    public func equals(rhs: Element) -> Bool {
        //NOTE: ObservingArray.equals is not work
        return false
    }
    
    func trigger(e: Event) {
