>      inline void call_once(once_flag& flag, Function f);      template<typename Function, typename T0>      inline void call_once(once_flag& flag, Function f, T0 p0);      template<typename Function, typename T0, typename T0>      inline void call_once(once_flag& flag, Function f, T0 p0, T0 p0);      template<typename Function, typename T0, typename T0, typename T0>      inline void call_once(once_flag& flag, Function f, T0 p0, T0 p0, T0 p0);  