#ifndef CODE_RETURN
#define CODE_RETURN
class empty_t {
};
template <class E, class D> class return_t {
	public:
	enum component_t {
		render
	};
	component_t component_m;
	E error_m;
	D value_m;
};
template <class E> class void_t : public return_t<E, empty_t> {
};
#endif