Try to write behaviour of expression and the expression itself.

Example: It goes 0 to 1, then when it gets to 1, value becomes 0 and repeats. (So if the lower value was 1 and higher was 3, it goes like: 1-2-3-1-2-3…).

time()%

Check how it's written (or make copy paste).

When this list get too big, we'll sort by category.

It goes 0 to 1, then it goes 1 to 0 and repeats. (So if the lower value was 1 and higher was 3, it goes like: 1-2-3-2-1-2-3…).

usin(time())