When inputting x-3(x<=0) and zooming in to some extent, you will see the left branch extend larger than 0, but not equal 0 and end up at (0,-3+). And the right branch a bit more than 0, that begins with (0+, 0+).
I think it not right. Do you think so?
The question was discovered by my student, Ma Chishuo. I'm not sure if it is a bug.