 }
 
 extension AnimationState {
-    var isCompleted: Bool {
+    public var isCompleted: Bool {
         switch self {
         case .Completed:
             return true

    private let animation: AnimationState -> Void
    private let id: String
    
    init(id: String, duration: NSTimeInterval, animation: AnimationState -> Void) {
        self.start = NSDate()
        self.duration = duration
        self.animation = animation

// MARK: Implementation


private final class PercentAnimator {
    
    private var animations: [Animation] = []
    
