Event handler function – did you know that?

private function buttonClick(e:MouseEvent):void {
          trace("button click");
}
 
/*If you write a function like this and you will call
 the buttonClick(); you will get an error that you 
havent provide the the Event.*/
 
private function buttonClick(e:MouseEvent = null):void {
          trace("button click");
}
 
/* if you try somethink like this, you can call
 the buttonClick() function whenever you like
 and you want get any errors!*/