Error # 1084 issue

Question

Trying to work through a tutorial and have got myself stumped.  The error is 1084: Syntax error: expecting rightparen before colon.
The function in question is _reverseString
package{
    import flash.display.*;
    import flash.net.*;
    public class main extends MovieClip{
    // variables
        private const maxCount:uint = 5;
        private const baseURL:String = "http://gtwebconcepts/tim";
        public var userName:String = "Timmy G";
        private var _countIndex:uint;
        private var _foundNumber:Boolean;
    //constructor
        public function main(){
            trace("can you hear me now?");
            //loadSite();
            //countLoop();
            _reverseString(val:String);//########## error 1084
            //_isEvenNumber(num:Object);
        //public methods
        public function loadSite():void{
            navigateToURL(new URLRequest(baseURL), "_blank");
        public function countLoop():void{
            for(var i:uint = 1; i<= maxCount; i++){
                trace("loop " +i+ " of  " + maxCount);
        //private methods
        private function _reverseString(str:String):String{
            var tmp:Array = str.split("").reverse();
            return tmp.join("");
        private function _isEvenNumber(num:Number):Boolean{
            return(num % 2 == 0);

Answer 1

you need to define val and use:
package{
    import flash.display.*;
    import flash.net.*;
    public class main extends MovieClip{
    // variables
        private const maxCount:uint = 5;
        private const baseURL:String = "http://gtwebconcepts/tim";
        public var userName:String = "Timmy G";
        private var _countIndex:uint;
        private var _foundNumber:Boolean;
    //constructor
        public function main(){
            trace("can you hear me now?");
            //loadSite();
            //countLoop();
            _reverseString(val);//########## error 1084
            //_isEvenNumber(num:Object);
        //public methods
        public function loadSite():void{
            navigateToURL(new URLRequest(baseURL), "_blank");
        public function countLoop():void{
            for(var i:uint = 1; i<= maxCount; i++){
                trace("loop " +i+ " of  " + maxCount);
        //private methods
        private function _reverseString(str:String):String{
            var tmp:Array = str.split("").reverse();
            return tmp.join("");
        private function _isEvenNumber(num:Number):Boolean{
            return(num % 2 == 0);