Function invoke

uspace/lib/cpp/include/__bits/functional/functional.hpp:46–49

    template<class F, class... Args>
    decltype(auto) invoke(F&& f, Args&&... args)
    {
        return aux::INVOKE(forward<F>(f),forward<Args>(args)...);
    }

    /**
     * 20.9.11, member function adaptors: