      * Returns the index of the first item in the array for which the predicate function
      * returns true, or -1 if no such item was found. The predicate function should be of type:
      *   function (element :*) :Boolean { }
+     *
+     * @return the zero-based index of the matching element, or -1 if none found.
      */
     public static function indexIf (arr :Array, predicate :Function) :int
     {

        return -1; // never found
    }

    public static function indexOf (arr :Array, element :Object) :int
    {
        if (arr != null) {

 * contains methods that understand the interfaces in this package.
 * So, for example, removeFirst() understands Equalable and will remove
 * an element that is equals() to the specified element, rather than just
 * === (strictly equals) to the specified element.
 */
public class ArrayUtil
{
