template<size_t N>
constexpr void satisfy(); // exposition only
template<size_t N>
constexpr void prev(); // exposition only
template<size_t N>
constexpr void advance-fwd(difference_type offset, difference_type steps); // exposition only
template<size_t N>
constexpr void advance-bwd(difference_type offset, difference_type steps); // exposition only
template<class... Args>
constexpr explicit iterator(maybe-const<Const, concat_view>* parent, // exposition only
Args&&... args)
requires constructible_from<base-iter, Args&&...>;
constexpr iterator(iterator<!Const> it)
requires Const &&
(convertible_to<iterator_t<Views>, iterator_t<const Views>> && ...);
constexpr decltype(auto) operator*() const;
constexpr iterator& operator++();
constexpr void operator++(int);
constexpr iterator operator++(int)
requires all-forward<Const, Views...>;
constexpr iterator& operator--()
requires concat-is-bidirectional<Const, Views...>;
constexpr iterator operator--(int)
requires concat-is-bidirectional<Const, Views...>;
constexpr iterator& operator+=(difference_type n)
requires concat-is-random-access<Const, Views...>;
constexpr iterator& operator-=(difference_type n)
requires concat-is-random-access<Const, Views...>;
constexpr decltype(auto) operator[](difference_type n) const
requires concat-is-random-access<Const, Views...>;
friend constexpr bool operator==(const iterator& x, const iterator& y)
requires (equality_comparable<iterator_t<maybe-const<Const, Views>>> && ...);
friend constexpr bool operator==(const iterator& it, default_sentinel_t);
friend constexpr bool operator<(const iterator& x, const iterator& y)
requires all-random-access<Const, Views...>;
friend constexpr bool operator>(const iterator& x, const iterator& y)
requires all-random-access<Const, Views...>;
friend constexpr bool operator<=(const iterator& x, const iterator& y)
requires all-random-access<Const, Views...>;
friend constexpr bool operator>=(const iterator& x, const iterator& y)
requires all-random-access<Const, Views...>;
friend constexpr auto operator<=>(const iterator& x, const iterator& y)
requires (all-random-access<Const, Views...> &&
(three_way_comparable<iterator_t<maybe-const<Const, Views>>> && ...));
friend constexpr iterator operator+(const iterator& it, difference_type n)
requires concat-is-random-access<Const, Views...>;
friend constexpr iterator operator+(difference_type n, const iterator& it)
requires concat-is-random-access<Const, Views...>;
friend constexpr iterator operator-(const iterator& it, difference_type n)
requires concat-is-random-access<Const, Views...>;
friend constexpr difference_type operator-(const iterator& x, const iterator& y)
requires concat-is-random-access<Const, Views...>;
friend constexpr difference_type operator-(const iterator& x, default_sentinel_t)
requires see below;
friend constexpr difference_type operator-(default_sentinel_t, const iterator& x)
requires see below;
friend constexpr decltype(auto) iter_move(const iterator& it) noexcept(see below);
friend constexpr void iter_swap(const iterator& x, const iterator& y) noexcept(see below)
requires see below;