message: Add locally nameless impl for Vec
diff: @@ -222,3 +222,20 @@ impl<T: LocallyNameless + Clone> LocallyNameless for Rc<T> {
  Rc::make_mut(self).open_at(index, on_bound);
  }
  }
  +
  +impl<T: LocallyNameless + Clone> LocallyNameless for [T] {
  + type FreeName = T::FreeName;
  + type BoundName = T::BoundName;
  +
  + fn close_at(&mut self, index: Debruijn, on_free: OnFreeFn<T::FreeName, T::BoundName>) {
  + for elem in self {
  + elem.close_at(index, on_free);
  + }
  + }
  +
  + fn open_at(&mut self, index: Debruijn, on_bound: OnBoundFn<T::FreeName, T::BoundName>) {
  + for elem in self {
  + elem.open_at(index, on_bound);
  + }
  + }
  +}
  