type Base;
type Derived;
impl Base {
  fn foo(a: String, b: String) {
    println "Base.foo(" + a + ", " + b + ")";
  }
}

impl Derived < Base {
  fn foo() {
    println "Derived.foo()"; // out: Derived.foo()
    super.foo("a", "b", "c", "d"); // out: TypeError: arity expected 2, got 4 name: "foo"
  }
}

Derived().foo();