strShuffle function
Randomly shuffles the received string and returns it.
Implementation
String strShuffle(String str) {
final List<int> codePoints = str.runes.toList();
final Random random = Random();
for (int i = codePoints.length - 1; i > 0; i--) {
int j = random.nextInt(i + 1);
int temp = codePoints[i];
codePoints[i] = codePoints[j];
codePoints[j] = temp;
}
return String.fromCharCodes(codePoints);
}