tailsString function
Returns a list of lists by removing one character at a time.
Implementation
List<String> tailsString(String s) {
List<int> codes = List.from(s.codeUnits);
List<String> result = [];
for (int i = 0; i < s.length; i++) {
result.add(String.fromCharCodes(codes));
codes.removeAt(0);
}
return result + [''];
}