34     requires(_Tp&& __t) {  in requires()  argument
35       bool(__t.empty());  in requires()
41     requires(_Tp&& __t) { ranges::size(__t); };
47     requires(_Tp&& __t) {
48       bool(ranges::begin(__t) == ranges::end(__t));
49       { ranges::begin(__t) } -> forward_iterator;
54     [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool operator()(_Tp&& __t) const  in operator()
55         noexcept(noexcept(bool(__t.empty()))) {  in operator()
56       return bool(__t.empty());  in operator()
60     [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool operator()(_Tp&& __t) const  in operator()
61         noexcept(noexcept(ranges::size(__t))) {  in operator()
62       return ranges::size(__t) == 0;  in operator()
66     [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool operator()(_Tp&& __t) const  in operator()
67         noexcept(noexcept(bool(ranges::begin(__t) == ranges::end(__t)))) {  in operator()
68       return ranges::begin(__t) == ranges::end(__t);  in operator()