I find true module to be an insanely useful operator. Python negative indexing (array[-1]) is essentially that. I’ve proposed it to swift but people didn’t see the point https://forums.swift.org/t/double-modulo-operator/2718
>>> a = [1, 2, 3]
>>> a[-1]
3
>>> a[-2]
2
>>> a[-3]
1
>>> a[-4]
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
IndexError: list index out of range