It's just fine for negatives. If you slide the range that 'makes sense' back by 10 (add -10 to it): -10 <= x < 0 This excludes the end of the range, it inclu

It's just fine for negatives. If you slide the range that 'makes sense' back by 10 (add -10 to it): -10 <= x < 0 This excludes the end of the range, it includes the start of the range. What's changed is that the start of the range is no longer at zero and also has crossed from positive to negative.