library /*isNonNullableByDefault*/;
import self as self;
import "dart:core" as core;

class B<X extends core::Object? = dynamic, Y extends core::Object? = dynamic> extends core::Object {
  synthetic constructor •() → self::B<self::B::X%, self::B::Y%>
    ;
}
class C<X extends core::Object? = dynamic, Y extends core::Object? = dynamic> extends core::Object {
  synthetic constructor •() → self::C<self::C::X%, self::C::Y%>
    ;
}
class D<X extends self::B<self::D::X, self::D::Y> = self::B<dynamic, dynamic>, Y extends self::C<self::D::X, self::D::Y> = self::C<dynamic, dynamic>, Z extends (self::D::Y) → self::D::X = (Never) → self::B<dynamic, dynamic>, W extends core::num> extends core::Object {
  synthetic constructor •() → self::D<self::D::X, self::D::Y, self::D::Z, self::D::W>
    ;
}
static method main() → dynamic
  ;