namespace std {
template<class Container>
class back_insert_iterator {
protected:
Container* container;
public:
using iterator_category = output_iterator_tag;
using value_type = void;
using difference_type = ptrdiff_t;
using pointer = void;
using reference = void;
using container_type = Container;
constexpr explicit back_insert_iterator(Container& x);
constexpr back_insert_iterator& operator=(const typename Container::value_type& value);
constexpr back_insert_iterator& operator=(typename Container::value_type&& value);
constexpr back_insert_iterator& operator*();
constexpr back_insert_iterator& operator++();
constexpr back_insert_iterator operator++(int);
};
}