狂欢控制器声明语法

Question

I am new to golang revel framework.

I have read revel tutorials and i see this lines at the top of each controller file:

type App struct {
    *revel.Controller
}

I suppose this mean my App class is derivated from Controller class.

Warning: i know the object model is not the same comparing to C++. I do not really think the word "derivated" are corrects in go...

My question is: What is the role of the asterix (*) before revel.Controller ?

Thanks