docs: def pre_dispatch(self, request, path_args):
          """
          Pre dispatch hook
          """
          secret_key = self.get_secret_key(request, path_args)
          if not secret_key:
              raise PermissionDenied('Signature not valid.')
  
          try:
              signing.verify_url_path(request.path, request.GET, secret_key)
          except SigningError as ex:
              raise PermissionDenied(str(ex))