Icons on badger2040?

I have a badger2040 and i am looking through the examples. In the launcher.py example on githhub on pimorini page there is icon presented when run. There is also reference to this on the badger2040 function reference. It says “Copies a portion from an icon sheet onto the screen at x/y.” What is an icon sheet? I cant find anything in the files relating to this. Is it a feature prebuilt into the module? what file format is it (png etc).

I have a bit of an explanation of how I used some additional custom icons on the Badger 2040 within this blog post, in case that helps.

Tufty2040 also has sprite sheets. I did a piece on them here:
Help with Tufty sprite sheets - Support - Pimoroni Buccaneers
A sprite sheet is a large ‘image’ which may be divided into individual sprites - small images - for use in your program/game.
Hope this helps.