anchor.diff:  /// its superclass. The actual argument will be checked at runtime to ensure it
   /// is a subtype of the overridden parameter type.
   ///
  -/// DEPRECATED: Use the `covariant` modifier instead.
  -@deprecated
  +@Deprecated('Use the `covariant` modifier instead')
   const _Checked checked = _Checked();
   
   /// Used to annotate a library, or any declaration that is part of the public
  
positive.code:   const _Sealed();
  }
  
  @deprecated
  class _Virtual {
    const _Virtual();
  }
  
negative.code: /// Deprecated: Most of strong mode is now the default in 2.0, but the notion of
  /// virtual fields was dropped, so this annotation no longer has any meaning.
  /// Uses of the annotation should be removed.
  @Deprecated('No longer has meaning')
  const _Virtual virtual = _Virtual();
  
  /// Used to annotate an instance member that was made public so that it could be
  