Maybe, I’m overthinking this, but while perusing the Ansible documentation I discovered
undef in filters section. There is an example of how to use, and a reference to it in the Ansible 2.8 Porting Guide, but haven’t found any more details on it. Is it something that is built into Ansible? Does it come from Python or Jinja2?
The optional hint option (wouldn’t have known it was optional until reading the porting guide) seems useful to provide information to a user one what variable is undefined in playbooks, etc.
Maybe it’s not very important, but it would be nice to have some more discoverable documentation for this and any other lesser-known functions in Ansible, even if it’s just a link to another site in the case of Python or Jinja2 stuff.