Method or_else

extlibs/sol3/include/sol/sol.hpp:4285–4291

		/// \synopsis template <class F> optional<T> or_else (F &&f) &&;
		template <class F, detail::enable_if_ret_void<F>* = nullptr>
		optional<T> or_else(F&& f) && {
			if (has_value())
				return std::move(*this);

			std::forward<F>(f)();
			return nullopt;
		}

		/// \exclude
		template <class F, detail::disable_if_ret_void<F>* = nullptr>