1 template<typename T>
2 struct make_signed
3 {
4   using type = int;
5 };
6 
7 template<typename S>
8 using make_signed_t = typename make_signed<S>::type;
9 
10 template<typename U>
11 auto ssize (U &parm) -> make_signed_t<decltype(parm.call())>;
12