FR: not-in either list functionality

[Mariusthvdb]

Describe the enhancement

we've recently seen additions for manipulating lists which are very welcome and super useful.

the one method we dont have , is an easy way to find items not in either list:
which is why Ive tried in home-assistant/core#124055 with template below in workarounds

Example usage

find entities that are in neither list

{% set groepen = states.light
|selectattr('attributes.entity_id','defined')
| map(attribute='entity_id')
|list %}

{% set leden = groepen| expand | map(attribute='entity_id')| list %}

{{not_in(groepen, leden)}}

Current workarounds

{% set groepen = states.light
|selectattr('attributes.entity_id','defined')
| map(attribute='entity_id')
|list %}

{% set leden = groepen| expand | map(attribute='entity_id')| list %}

{{ states.light
    | map(attribute='entity_id')
    | reject('in', groepen +leden)
    | list}}

Anything else?

No response