package domain type User interface { GetUsername() string GetState() UserState } type UserState int32 const ( UserStateUnspecified UserState = iota UserStateActive UserStateInactive UserStateDeleted UserStateLocked UserStateSuspend UserStateInitial userStateCount ) func (f UserState) Valid() bool { return f >= 0 && f < userStateCount } func (s UserState) Exists() bool { return s != UserStateUnspecified && s != UserStateDeleted }