docs: def validate_unique_slug(self, cleaned_data):
          """
          Test whether the slug is unique within a given time period.
          """
          date_kwargs = {}
          error_msg = _("The slug is not unique")
  
          # The /year/month/slug/ URL determines when a slug can be unique.
          pubdate = cleaned_data['publication_date'] or now()
          if '{year}' in appsettings.FLUENT_BLOGS_ENTRY_LINK_STYLE:
              date_kwargs['year'] = pubdate.year
              error_msg = _("The slug is not unique within it's publication year.")
          if '{month}' in appsettings.FLUENT_BLOGS_ENTRY_LINK_STYLE:
              date_kwargs['month'] = pubdate.month
              error_msg = _("The slug is not unique within it's publication month.")
          if '{day}' in appsettings.FLUENT_BLOGS_ENTRY_LINK_STYLE:
              date_kwargs['day'] = pubdate.day
              error_msg = _("The slug is not unique within it's publication day.")
  
          date_range = get_date_range(**date_kwargs)
  
          # Base filters are configurable for translation support.
          dup_filters = self.get_unique_slug_filters(cleaned_data)
          if date_range:
              dup_filters['publication_date__range'] = date_range
  
          dup_qs = EntryModel.objects.filter(**dup_filters)
  
          if self.instance and self.instance.pk:
              dup_qs = dup_qs.exclude(pk=self.instance.pk)
  
          # Test whether the slug is unique in the current month
          # Note: doesn't take changes to FLUENT_BLOGS_ENTRY_LINK_STYLE into account.
          if dup_qs.exists():
              raise ValidationError(error_msg)