library;
import self as self;
import "dart:core" as core;

class A extends core::Object {
  synthetic constructor •() → void
    : super core::Object::•()
    ;
}
class B extends self::A {
  synthetic constructor •() → void
    : super self::A::•()
    ;
}
class C extends core::Object {
  synthetic constructor •() → void
    : super core::Object::•()
    ;
  method f1(self::A x) → void {}
  method f2([self::A x = null]) → void {}
  method f3({self::A x = null}) → void {}
  method f4() → self::A {}
}
class D extends self::C {
  synthetic constructor •() → void
    : super self::C::•()
    ;
  method f1(core::Object x) → void {}
  method f2([core::Object x = null]) → void {}
  method f3({core::Object x = null}) → void {}
  method f4() → self::B {}
}
class E extends self::C {
  synthetic constructor •() → void
    : super self::C::•()
    ;
  method f1(self::B x) → void {}
  method f2([self::B x = null]) → void {}
  method f3({self::B x = null}) → void {}
  method f4() → core::Object {}
}
static method main() → dynamic {}