{FR] In frontmatter checkbox sources, allow to test for existence/non-existence as well as checked/not checked

[ksdavidc]

Problem

When using some checkboxes, the value can be true or false (checked/unchecked), and it would be nice to create a loom that showed both values at the same time (i.e. if the key exists or not, not just if it has a particular value). That way, for example, one could toggle the values on and off from one loom, instead of needing two looms, one for checked, one for not checked.

This came up for me when using it with the digital garden plugin, but I can imagine other instances.

Solution

see above

Additional details

No response