

I don’t think this is implemented in the standard datetime library, but in principle overriding sub is easily possible and you can define it as you’d wish.
However, I think subtracting a year is a bit ill defined, because it isn’t clear which year you’re subtracting given the leap year issue.








I use cura as slicer and onshape for modeling. Onshape is browser-based and I found f360 to be a bit more intuitive, but it’s fully featured and works well.