Expected type 'timedelta', got 'DateTimeField' instead怎么回事，如何解决？

import datetime
from django.db import models
from django.utils import timezone


class Question(models.Model):
    question_text = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')

    def __str__(self):
        return self.question_text

    def was_published_recently(self):
        return self.pub_date >= timezone.now() - datetime.timedelta(days=1)

其中
return self.pub_date >= timezone.now() - datetime.timedelta(days=1)
这句中self.pub_date存在问题
Expected type 'timedelta', got 'DateTimeField' instead 14
这是怎么回事？怎么解决？

return self.pub_date ＞ datetime.timedelta(days=1)).timestamp()