code: def authorized_tenants(self):
          
          if self.is_authenticated and self._authorized_tenants is None:
              endpoint = self.endpoint
              try:
                  self._authorized_tenants = utils.get_project_list(
                      user_id=self.id,
                      auth_url=endpoint,
                      token=self.unscoped_token,
                      is_federated=self.is_federated)
              except (keystone_exceptions.ClientException,
                      keystone_exceptions.AuthorizationFailure):
                  LOG.exception('Unable to retrieve project list.')
          return self._authorized_tenants or []
docs: Returns a memoized list of tenants this user may access.