def get_full_name(self):        raise NotImplementedError()def get_short_name(self):        raise NotImplementedError()

import refrom time import timezonefrom django.contrib.auth.models AbstractBaseUser, BaseUserManagerfrom django.core import validatorsclass UserManager(BaseUserManager):    def create_user(self, username, email=None, password=None, **extra_fields):        """        Creates and saves a User with the given username, email and password.        """        now = timezone.now()        if not username:            raise ValueError(‘The given username must be set‘)        email = UserManager.normalize_email(email)        user = self.model(username=username, email=email,                          is_staff=False, is_active=True,                          last_login=now, date_joined=now, **extra_fields)        user.set_password(password)        user.save(using=self._db)        return user    def create_superuser(self, username, email, password, **extra_fields):        u = self.create_user(username, email, password, **extra_fields)        u.is_staff = True        u.is_active = True        u.save(using=self._db)        return uclass Users(AbstractBaseUser):    username = models.CharField(_(‘username‘), max_length=30, unique=True,        help_text=_(‘少于30个字符组成‘),validators=[            validators.RegexValidator(re.compile(‘^[\w.@+-]+$‘), _(‘Enter a valid username.‘), ‘invalid‘)        ])    email = models.EmailField(_(‘email address‘), blank=True)    is_staff = models.BooleanField(default=False, verbose_name=‘系统管理员‘)    is_teacher = models.BooleanField(‘是否是教师‘, default=False)    is_student = models.BooleanField(‘是否是学校‘, default=False)    is_school_manager = models.BooleanField(‘是否是学校管理员‘, default=False)    is_college_manager = models.BooleanField(‘是否是学院管理员‘, default=False)    date_joined = models.DateTimeField(_(‘date joined‘), default=0)    objects = UserManager()    USERNAME_FIELD = ‘username‘    REQUIRED_FIELDS = [‘email‘]    class Meta:        verbose_name = "用户"        verbose_name_plural = "用户"    def get_full_name(self):        return self.username + "-" + self.email    def get_short_name(self):        return self.username