Gold per second "Update Can Not Be A Corountine"

want a very simple script to add “Gold” every second like in league of ledgends for example.
however i dont understand the error.

#pragma strict

//function updates and gives X amount of Gold per second.
function Update () {yield WaitForSeconds (0.4);{
GOLD.Gold += 1;


another alternative solution could be:

function Start(){

function addGold(){;

If you want something per second try this:

var gold : float;

function Update(){
    gold +=Time.deltaTime;

You can read about time.deltatime here: Unity - Scripting API: Time.deltaTime. Also, if you want to use yield, you might want to read about Ienumerator’s. Also, here is something on corountines :