How do I access SystemDoNotDisturbState variable in javascript action?

Running BTT 3.560 on MacOS 11.3.

I'm trying to access the Do Not Disturb state in a javascript action, but I can't work out from the docs how to access it.

There seem to be two functions to get variables, but only strings or numbers, both of which result in undefined.

Here's what I have so far...

(async ()=> {

	const dnd = await callBTT('get_number_variable', {variable_name:'SystemDoNotDisturbState'});
	if(dnd === true) {
		let result = await callBTT('execute_assigned_actions_for_trigger', {uuid: 'ECD11D87-F5F6-41E1-9576-3DAAF2E8EDE4'});
		// Currently only the Apple Script and Shell Script actions return results.
	} else {

I'm trying to turn DND on and off on a cron trigger, but the actions avilable only allow toggle. I also have a manual control to toggle on demand.