          * @return  A new stream that contains the items from this stream followed by items from the parameters.
          * @example
          * <pre>
+         *     var a:Stream = $(1, 2);
+         *     var b:Stream = $(3);
+         *     var s:Stream = a.concat(b);
+         *     trace(s);
+         *     //Stream{1, 2, 3}
          * </pre>
          */
         public function concat(...rest):Stream

         * @return A new Dictionary from the current stream using specified property values as keys.
         * @example
         * <pre>
         * </pre>
         */
        public function dictionary(property:String, weak:Boolean = false):Dictionary

         * @return A new Dictionary or custom class created from <i>factory</i> which contains groups.
         * @example
         * <pre>
         *     public class Groups
         *     {
         *        public var key1:Stream;
         *        public var key2:Stream;
         *     }
         *
         *     var item1:Object = {id: 1, key: "key1"};
         *     var item2:Object = {id: 2, key: "key1"};
         *     var item3:Object = {id: 3, key: "key2"};
         *     var s:Stream = $(item1, item2, item3);
         *     var d:Groups = s.group("key", Groups);
         *     trace(d.key1);
         *     //Stream{item1, item2}
         *     trace(d.key2);
         *     //Stream{item3}
         * </pre>
         */
        public function group(callback:Function, factory:Class = null):*
