Flutter dart create random strings

Create a string util file with the following, StringUtil.dart

import 'dart:math';

const _chars = 'AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz1234567890';
Random _rnd = Random();

String getRandomString(int length) => String.fromCharCodes(
    Iterable.generate(
        length, (_) => _chars.codeUnitAt(_rnd.nextInt(_chars.length))
    )
);

Use the getRandomString in other dart files like the following. This creates 20 random strings, each string with a length of at least 5 and at most 20.

import 'StringUtil.dart';
final randomStringList = List.generate(20, (i) => getRandomString(5 + Random().nextInt(15)));