code: def has_urls(self):
          "Handy for templates."
          if self.isbn_uk or self.isbn_us or self.official_url or self.notes_url:
              return True
          else:
              return Falsf has_urls(self):
          "Handy for templates."
          if self.isbn_uk or self.isbn_us or self.official_url or self.notes_url:
              return True
          else:
              return False
docs: Handy for templates.