UnsafeJson
Design note: we could require the position in the stream here to improve debugging messages. But the cost would be that the RetractReader would need to keep track and any wrappers would need to preserve the position. It may still be desirable to do this but at the moment it is not necessary.
trait Product
trait Equals
trait NoStackTrace
class Exception
class Throwable
trait Serializable
class Object
trait Matchable
class Any