num property
final
Unique number of this MyUser.
num is intended for an easier MyUser identification by other User
s.
It's just like a telephone number in a real life.
num allows MyUser to perform a sign-in, when combined with a password.
It may be reused by another User in future, once this MyUser becomes
unreachable (sign-in for this MyUser is impossible).
Implementation
final UserNum num;