#
namespace std {
class partial_ordering;
class weak_ordering;
class strong_ordering;
constexpr bool is_eq (partial_ordering cmp) noexcept { return cmp == 0; }
constexpr bool is_neq (partial_ordering cmp) noexcept { return cmp != 0; }
constexpr bool is_lt (partial_ordering cmp) noexcept { return cmp < 0; }
constexpr bool is_lteq(partial_ordering cmp) noexcept { return cmp <= 0; }
constexpr bool is_gt (partial_ordering cmp) noexcept { return cmp > 0; }
constexpr bool is_gteq(partial_ordering cmp) noexcept { return cmp >= 0; }
template<class. Ts>
struct common_comparison_category {
using type = see below;
};
template<class. Ts>
using common_comparison_category_t = common_comparison_category<Ts..>::type;
template<class T, class Cat = partial_ordering>
concept three_way_comparable = see below;
template<class T, class U, class Cat = partial_ordering>
concept three_way_comparable_with = see below;
template<class T, class U = T> struct compare_three_way_result;
template<class T, class U = T>
using compare_three_way_result_t = compare_three_way_result<T, U>::type;
struct compare_three_way;
inline namespace unspecified {
inline constexpr unspecified strong_order = unspecified;
inline constexpr unspecified weak_order = unspecified;
inline constexpr unspecified partial_order = unspecified;
inline constexpr unspecified compare_strong_order_fallback = unspecified;
inline constexpr unspecified compare_weak_order_fallback = unspecified;
inline constexpr unspecified compare_partial_order_fallback = unspecified;
}
template<class T, class U>
struct type_order;
template<class T, class U>
constexpr strong_ordering type_order_v = type_order<T, U>::value;
}