WTH: day helper

Some releases ago the helper collection was expanded with the schedule helper.
It would be great if there is also a day helper.

The helper returns the value of true/false for a day.

For example. You create a day helper called vacation. Select all the vacation days.
And use this helper in an automation which controls your heating. So delay the start of the heating based on the day vacation helper.

Possible duplicate of WTH Why isn’t there a date range or month condition?

You already have calendar. Don’t see this would add anything more?