         ObservingUnwatch(self, target)
     }
     
+    public func equals(rhs: Element) -> Bool {
+        return self.equatable(newValue: rhs, oldValue: self.value)
+    }
+    
     func trigger(e: Event) {
         
         ObservingTrigger(self, e)

    public func unwatch(target: AnyObject) {
        
        ObservingUnwatch(self, target)
    }
    
    func trigger(e: Event) {

    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) {
