Function isOdd

Examples/NoModules/Appendix A/ExA_12/ProperMath.h:10–10

enum class Oddity { Even, Odd };
inline bool isOdd(int x) { return x % 2 != 0; }
inline auto getOddity(int x) { return isOdd(x) ? Oddity::Odd : Oddity::Even; }

#endif