import 'dart:math'; class Global { static String generateCode( [int length = 16, String chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"]) { var rand = Random(); return String.fromCharCodes(Iterable.generate( length, (_) => chars.codeUnitAt(rand.nextInt(chars.length)))); } }