type SomeIter<'a, E, Ix> = Map<Zip<Enumerate<Iter<'a, WSuc<E, Ix>>>, Repeat<Ix>>, fn(((usize, &'a WSuc<E, Ix>), Ix)) -> EdgeReference<'a, E, Ix>>;
struct SomeIter<'a, E, Ix> { /* private fields */ }