def clean(self):
        if not self.publishable:
            return

        if self.publish_from and self.publish_from < self.publishable.publish_from:
            raise ValidationError(_('A publishable cannot be listed before it\'s published.'))

        if self.publishable.publish_to:
            if not self.publish_to or self.publishable.publish_to > self.publish_to:
                raise ValidationError(_('A publishable cannot be listed longer than it\'s published.'))
dataset/ETHPy150Open ella/ella/ella/core/models/publishable.py/Listing.clean/swapped operands of `>`