code: func updateImportedPolicy(c context.Context, name, rev, sha256 string, serialized []byte) error {
  	header := &importedPolicyHeader{
  		Name:     name,
  		Revision: rev,
  		SHA256:   sha256,
  	}
  	body := &importedPolicyBody{
  		Parent:   datastore.KeyForObj(c, header),
  		Revision: rev,
  		SHA256:   sha256,
  		Data:     serialized,
  	}
  	return transient.Tag.Apply(datastore.RunInTransaction(c, func(c context.Context) error {
  		return datastore.Put(c, header, body)
  	}, nil))
  }
docs: // updateImportedPolicy replaces the currently stored policy.
  //
  // It transactionally updates both importedPolicyHeader and importedPolicyBody.