Pre-emptive code formatting check?

[rod-glover]

The Python CI action (and most others) takes a long time to run, on the order of 15 minutes. This is due to the install step. What I've had happen several times is that this action fails right at the end because the code formatting checker (Black now) raises an error.

It would be better if this check were done immediately after the code checkout step, and maybe short-circuited the whole thing or otherwise indicated failure early. (Of course, it would be better if I checked my code before every push, but I don't always.) Is this possible?