docs: def _check_endings(self):
          """Check begin/end of slug, raises Error if malformed."""
          if self.slug.startswith("/") and self.slug.endswith("/"):
              raise InvalidSlugError(
                  _("Invalid slug. Did you mean {}, without the leading and trailing slashes?".format(self.slug.strip("/"))))
          elif self.slug.startswith("/"):
              raise InvalidSlugError(
                  _("Invalid slug. Did you mean {}, without the leading slash?".format(self.slug.strip("/"))))
          elif self.slug.endswith("/"):
              raise InvalidSlugError(
                  _("Invalid slug. Did you mean {}, without the trailing slash?".format(self.slug.strip("/"))))