Dart forEach() on a Map

foreachmap.dart

main() {
    Map<String, int> map = {
        'one': 1,
        'two': 2,
        'twelve': 12};

    void iterateMapEntry(key, value) {
      map[key] = value;
      print('$key:$value');//string interpolation in action
    }
    map.forEach(iterateMapEntry);
}

What about the Index?
int i=0;
void iterateMapEntry(key, value) {
map[key] = value;
print('$key:$value at $i');//string interpolation in action
i++;
}