namespace std {
template<class Callback>
class stop_callback {
public:
using callback_type = Callback;
template<class C>
explicit stop_callback(const stop_token& st, C&& cb)
noexcept(is_nothrow_constructible_v<Callback, C>);
template<class C>
explicit stop_callback(stop_token&& st, C&& cb)
noexcept(is_nothrow_constructible_v<Callback, C>);
~stop_callback();
stop_callback(const stop_callback&) = delete;
stop_callback(stop_callback&&) = delete;
stop_callback& operator=(const stop_callback&) = delete;
stop_callback& operator=(stop_callback&&) = delete;
private:
Callback callback;
};
template<class Callback>
stop_callback(stop_token, Callback) -> stop_callback<Callback>;
}