How to identify issues with no labels?

According to this example: https://gitlab.com/gitlab-org/gitlab-triage/blob/master/support/.triage-policies.example.yml

labels:
  - No label
state: opened

will do the trick, but my tests show different.

According to documentation, there is no test for no labels. The rule above will search for a label No label, but this does not exist. thus the result set is empty.

Is there a list of triage examples or a list of triage snippets?