dunno yet
- += (str)
- += (num)
- %
let input = 0;
(input += String(input += 1)) % 6;
// input: (number, 0)
input += 1;
// input: (number, 1)
String(input);
// (string, "1")
input += "1";
// input: (string, "11")
"11" % 6;
// (number, 5)
input += "1"; // when input is a number
%
strange: same output, even with top line uncommented