     *
     *  @param label (can be nil)
     */
-    init(serial label: String?) {
+    public init(serial label: String?) {
         if label != nil {
             dispatchQueue = dispatch_queue_create(label!, DISPATCH_QUEUE_SERIAL)
         }

    *  @param GCDClosure
    *
    */
    func asyncBarrier(closure: GCDClosure) {
        dispatch_barrier_async(dispatchQueue, closure)
    }
   

    *
    *  @return
    */
    public class func once(predicate: UnsafeMutablePointer<dispatch_once_t>, closure: GCDClosure) {
        dispatch_once(predicate, closure)
    }
}