abstract class A extends Enum {
  int get foo => index;
}

abstract class B implements Enum {
  int get foo => index;
}

enum EA with A { element }

enum EB with B { element }

enum EM with M { element }

enum EN with N { element }

expectEquals(x, y) {}
main() {}
mixin M on Enum {
  int get foo => index;
}
mixin N implements Enum {
  int get foo => index;
}