code: def pre_save(self, instance, add: bool):
          
  
          if not isinstance(instance, AtomicSlugRetryMixin):
              raise ImproperlyConfigured((
                  'Model \'%s\' does not inherit from AtomicSlugRetryMixin. '
                  'Without this, the LocalizedUniqueSlugField will not work.'
              ) % type(instance).__name__)
  
          slugs = LocalizedValue()
  
          for lang_code, value in self._get_populate_values(instance):
              if not value:
                  continue
  
              slug = slugify(value, allow_unicode=True)
  
              # verify whether it's needed to re-generate a slug,
              # if not, re-use the same slug
              if instance.pk is not None:
                  current_slug = getattr(instance, self.name).get(lang_code)
                  if current_slug is not None:
                      stripped_slug = current_slug[0:current_slug.rfind('-')]
                      if slug == stripped_slug:
                          slugs.set(lang_code, current_slug)
                          continue
  
              if self.include_time:
                  slug += '-%d' % datetime.now().microsecond
  
              retries = getattr(instance, 'retries', 0)
              if retries > 0:
                  # do not add another - if we already added time
                  if not self.include_time:
                      slug += '-'
                  slug += '%d' % retries
  
              slugs.set(lang_code, slug)
  
          setattr(instance, self.name, slugs)
          return slugs
docs: Ran just before the model is saved, allows us to built
          the slug.
  
          Arguments:
              instance:
                  The model that is being saved.
  
              add:
                  Indicates whether this is a new entry
                  to the database or an update.
  
          Returns:
              The localized slug that was generated.