14 typename T::mapped_type;
15 typename T::value_type;
16 { std::declval<typename T::value_type>().second } -> std::convertible_to<typename T::mapped_type>;
17 { v.begin() } -> std::forward_iterator;
18 { v.end() } -> std::forward_iterator;
19 { v.find(std::declval<typename T::key_type>()) } -> std::same_as<typename T::iterator>;