private function a(e:Event):void {
trace("a");
}
private function b(e:Event):void {
trace("b");
}
private function c(e:Event):void {
trace("c");
}
private function initApp():void {
b1.addEventListener(MouseEvent.CLICK, a, false, 1);
b1.addEventListener(MouseEvent.CLICK, c, false, 2);
b1.addEventListener(MouseEvent.CLICK, b, false, 3);
}