go - Golang how to do type assertion for unknown interface?

Question

I understand that I can get an object's value by reflection and then use type assertion to get back the actual object using:

obj := new(User)
out := reflect.ValueOf(obj).Elem().Interface().(User)
fmt.Println(out == *obj) // true

But what if I don't know that the object's type is User, how can I do type assertion? Say it was inside a function like:

func Foo(obj interface{}) bool {
    // out := reflect.ValueOf(obj).Elem().Interface().( ... )
    return out == *obj
}

func main() {
    obj := new(User)
    fmt.Println(Foo(obj))
}

Inside the Foo function you'll never know what type of object will actually be passed and so how do you complete the type assertion?

Answer 1

Waitting for answers