Dart: Access Mixins and Class instance variables

mixins.dart

mixin Address on Person {
  late final String address;

  say() {
    print("Name: $name, Address: $address");
  }
}

class Person {
  late final String name;

  Person(this.name);
}

class Child extends Person with Address {
  Child(super.name, address) {
    this.address = address;
  }
}

void main() {
  final one = Child("Robs Oliver", "1st St. Wonderland");
  one.say();
}