extern bool operator> (Time const & a, Time const & b);
extern bool operator>= (Time const & a, Time const & b);
extern std::ostream & operator<< (std::ostream & s, Time const & t);
extern bool operator> (Time const & a, Time const & b);
extern bool operator>= (Time const & a, Time const & b);
extern std::ostream & operator<< (std::ostream & s, Time const & t);