class TimedModel(models.Model):
    """
    Model with created field
    """
    class Meta:
        abstract = True
    class Admin:
        pass
    created_at = models.DateTimeField(auto_now_add=True)

class TimedModelUp(models.Model):
    """
    Model with updated at field
    """
    class Meta:
        abstract = True
    updated_at = models.DateTimeField(auto_now=True)