- auto begin() const { return powerset_iterator<Iterable::iterator>(iterable.begin(), iterable.end()); }
- auto end() const { return powerset_iterator<Iterable::iterator>(); }
+ auto begin() const { return powerset_iterator<typename Iterable::const_iterator>(iterable.begin(), iterable.end()); }
+ auto end() const { return powerset_iterator<typename Iterable::const_iterator>(); }