How to get number of buried cards for the day?


I am the author of Review Statistics During Review (Cards done, Left, s/card, spent, left, ETA) - AnkiWeb

I’d like to update the total by subtracting the number of buried cards as seen after the plus signs in this picture:

How does one do that?

If you look at the source code of that screen, you’ll see they are derived by comparing the due values from the deck list.

Would you know how to call for that in an addon? I’d like to subtract the plus values from my addon’s total cards left value.