inline bool operator==(const SignedId &other) const { return id == other.id; }
inline bool operator!=(const SignedId &other) const { return id != other.id; }
inline bool operator<(const SignedId &other) const { return id < other.id; }
+ inline bool operator<=(const SignedId &other) const { return id <= other.id; }
inline bool operator>(const SignedId &other) const { return id > other.id; }
inline bool operator>=(const SignedId &other) const { return id >= other.id; }
inline bool operator==(int i) const { return id == i; }