*<Null safety>*
void shuffle (List elements, [int start = 0, int? end, Random? random])
void shuffle(List elements, [int start = 0, int? end, Random? random]) { random ??= Random(); end ??= elements.length; var length = end - start; while (length > 1) { var pos = random.nextInt(length); length--; var tmp1 = elements[start + pos]; elements[start + pos] = elements[start + length]; elements[start + length] = tmp1; } }