An over-engineered FizzBuzz implementation.
/* OUTPUT 1 2 Fizz 4 Buzz */ ```
fb = fb + ("Kazz", 7); fb += ("Vezz", 11);
let left = fb.compute(3 * 5 * 7 * 11); let right = "FizzBuzzKazzVezz";
assert_eq!(left, right); ```
let left = (1..=5).fizzbuzz_custom(fb).collect::
assert_eq!(left, right); ```
for i in 1..100 { let res = fb.compute(i); println!("{res}"); } ```