code: def get_queryset(self):
          
  
          queryset = super(SingletonManager, self).get_queryset()
  
          # Get current site
          current_site = None
          if getattr(settings, 'SITE_ID', None) is not None:
              current_site = Site.objects.get_current()
  
          # If site found limit queryset to site.
          if current_site is not None:
              queryset = queryset.filter(sites=settings.SITE_ID)
  
          if not queryset.exists():
              # Create object (for current site) if it doesn't exist.
              obj = self.model.objects.create()
              if current_site is not None:
                  obj.sites.add(current_site)
  
          return queryset
docs: Return the first preferences object for the current site.
          If preferences do not exist create it.