How do you pass a function as a parameter

Main.class

modalWindow = new ModalWindow();
modalWindow.param1 = 5;
modalWindow.paramFunction = myPublicFunction;
modalWindow.show();

public function  myPublicFunction(param:int):int{
    return param*10;
}

ModalWindow.class

class ModalWindow{
   var param1:int;
   var paramFunction:Function;
    public ModalWindow(){
        Alert.show( paramFunction(param1+10) );
    }
}