      - parameter completionHandler: Callback with Classifer?
      */
     public func getClassifier(classifierId: String,
-        completionHandler: (Classifier?, NSError?) -> ()) {
+        completionHandler: (Classifier?, NSError?) -> Void) {
             
         // construct request
         let request = WatsonRequest(

     - parameter completionHandler: Callback with Classification?
     */
    public func classify(classifierId: String, text: String,
        completionHandler: (Classification?, NSError?) -> ()) {
        
        // construct request
        let request = WatsonRequest(

     - parameter classifierId:      The classifer ID used to delete the classifier
     - parameter completionHandler: Bool return with true as success
     */
    public func deleteClassifier(classifierId: String, completionHandler: NSError? -> Void) {
        
        // construct request
        let request = WatsonRequest(
