Struct inside a class: How to get outer?

[Nick Sabalausky (Abscissa) via Digitalmars-d-learn]

Is this even possible? My attempts:

class Outer {
        struct Inner {
                void foo() {
                        // Error: no property 'outer' for type 'Inner'
                        Outer o = this.outer;

                        // Error: cannot implicitly convert expression
                        // this of type Inner to testNested.Outer
                        Outer o = this;
                }
        }
}