code: def _taglist(self, other_model=None, queryset=None):
          
          from taggit.models import TaggedItem
          filter = None
          if queryset is not None:
              filter = set()
              for item in queryset.all():
                  filter.update(item.tags.all())
              filter = set([tag.id for tag in filter])
          elif other_model is not None:
              filter = set(TaggedItem.objects.filter(
                  content_type__model=other_model.__name__.lower()
              ).values_list('tag_id', flat=True))
          tags = set(TaggedItem.objects.filter(
              content_type__model=self.model.__name__.lower()
          ).values_list('tag_id', flat=True))
          if filter is not None:
              tags = tags.intersection(filter)
          return list(tags)
docs: Restituisce una lista di id di tag comuni al model corrente e al model
          o queryset passati come argomento