static constexpr decltype(auto) get-element(const iterator_t<Base>& i);
constexpr explicit iterator(iterator_t<Base> current);
constexpr iterator(iterator<!Const> i)
requires Const && convertible_to<iterator_t<V>, iterator_t<Base>>;
constexpr const iterator_t<Base>& base() const & noexcept;
constexpr iterator_t<Base> base() &&;
constexpr iterator& operator++();
constexpr void operator++(int);
constexpr iterator operator++(int) requires forward_range<Base>;
constexpr iterator& operator--() requires bidirectional_range<Base>;
constexpr iterator operator--(int) requires bidirectional_range<Base>;
constexpr iterator& operator+=(difference_type n)
requires random_access_range<Base>;
constexpr iterator& operator-=(difference_type n)
requires random_access_range<Base>;
friend constexpr bool operator==(const iterator& x, const iterator& y)
requires equality_comparable<Base>;
friend constexpr bool operator<(const iterator& x, const iterator& y)
requires random_access_range<Base>;
friend constexpr bool operator>(const iterator& x, const iterator& y)
requires random_access_range<Base>;
friend constexpr bool operator<=(const iterator& x, const iterator& y)
requires random_access_range<Base>;
friend constexpr bool operator>=(const iterator& x, const iterator& y)
requires random_access_range<Base>;
friend constexpr auto operator<=>(const iterator& x, const iterator& y)
requires random_access_range<Base> && three_way_comparable<iterator_t<Base>>;
friend constexpr iterator operator+(const iterator& x, difference_type y)
requires random_access_range<Base>;
friend constexpr iterator operator+(difference_type x, const iterator& y)
requires random_access_range<Base>;
friend constexpr iterator operator-(const iterator& x, difference_type y)
requires random_access_range<Base>;
friend constexpr difference_type operator-(const iterator& x, const iterator& y)
requires sized_sentinel_for<iterator_t<Base>, iterator_t<Base>>;