randomString function
Implementation
String randomString(int len) {
var r = Random();
const chars =
'AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz1234567890';
return List.generate(len, (index) => chars[r.nextInt(chars.length)]).join();
}