abstract class A extends Enum {
  int get foo => index;
}
enum EA with A { element }
abstract class B implements Enum {
  int get foo => index;
}
enum EB with B { element }
mixin M on Enum {
  int get foo => index;
}
enum EM with M { element }
mixin N implements Enum {
  int get foo => index;
}
enum EN with N { element }
expectEquals(x, y) {}
main() {}