docs: def InferUserAndSubjectFromUrn(self):
      """Infers user name and subject urn from self.urn."""
      _, cron_str, cron_job_name, user, _ = self.urn.Split(5)
  
      if cron_str != "cron":
        raise access_control.UnauthorizedAccess(
            "Approval object has invalid urn %s." % self.urn,
            requested_access=self.token.requested_access)
  
      return (user, aff4.ROOT_URN.Add("cron").Add(cron_job_name))