def METHOD_NAME(self, instance, **kwargs):
    """
    Signal handlers don't have access to the previous version of
    an object so we have to load it from the database!
    """
    if kwargs.get("raw", False):
        return
    if instance.pk and hasattr(instance, "history"):
        instance.previous = instance.__class__.objects.filter(
            pk=instance.pk
        ).first()