老师好，我重载__unicode方法，为啥页面显示还是EmailVerifyRecord object，下面是我重载的代码

class EmailVerifyRecord(models.Model):
   code = models.CharField(max_length=20,verbose_name=u"验证码")
   email = models.EmailField(max_length=50,verbose_name=u"邮箱")
   send_type = models.CharField(verbose_name="验证码类型",choices=(("register",u"注册"),("forget",u"找回密码")),max_length=10)
   send_time = models.DateTimeField(verbose_name="发送时间",default=datetime.now)

   class Meta:
       verbose_name = u"邮箱验证码"
       verbose_name_plural = verbose_name

       def __unicode__(self):
           return '{1}({2})'.format(self.code, self.email)