| library /*isNonNullableByDefault*/; | 
 | import self as self; | 
 | import "dart:core" as core; | 
 |  | 
 | class Foo<S extends core::num> extends core::Object { | 
 |   synthetic constructor •() → self::Foo<self::Foo::S> | 
 |     : super core::Object::•() | 
 |     ; | 
 |   method test1(covariant-by-class self::Foo::S x) → void { | 
 |     (self::Foo::S) → self::Foo::S f = self::Test|get#test<self::Foo::S>(x); | 
 |   } | 
 | } | 
 | extension Test<T extends core::Object? = dynamic> on T% { | 
 |   get test = self::Test|get#test; | 
 | } | 
 | static method Test|get#test<T extends core::Object? = dynamic>(lowered final self::Test|get#test::T% #this) → (self::Test|get#test::T%) → self::Test|get#test::T% | 
 |   return (self::Test|get#test::T% a) → self::Test|get#test::T% => #this; | 
 | static method main() → void {} |