public IUser ChangeUserPassword(string userName, string password, string newPassword)
        {
            IRegistrantUser user = this.CreateUser(userName, password);

            user.ChangePassword(newPassword);
            return(user);
        }
        public IUser RegisterUser(string userName, string password)
        {
            IRegistrantUser user = this.CreateUser(userName, password);

            user.Register();
            return(user);
        }