Hole Callout Check

This isn't a troubleshooting problem, just something I'm wondering about.

I wrote a macro that checks whether or not all of the hole features in a part have a corresponding hole callout somewhere on the active drawing document.

As I was testing this thing, I was reminded that Solidworks does a redundancy check when the user is adding hole callouts for HoleWizard features that already have a corresponding callout.

This leads me to wonder, how is this check implemented? Is it exposed somewhere in the API? Is there already a tool that performs this check better than mine can?

I had to do some shenanigans in order to collect my list of hole features and associate the hole callouts with their respective HoleWizardFeatures.