anchor.diff:    /**
      * The unique instance of this class.
      */
  -  static VoidTypeImpl _INSTANCE = new VoidTypeImpl();
  -
  -  /**
  -   * Return the unique instance of this class.
  -   */
  -  static VoidTypeImpl get instance => _INSTANCE;
  +  static final VoidTypeImpl instance = new VoidTypeImpl._();
   
     /**
      * Prevent the creation of instances of this class.
      */
  -  VoidTypeImpl() : super(null, Keyword.VOID.syntax);
  +  VoidTypeImpl._() : super(null, Keyword.VOID.syntax);
   
     @override
     int get hashCode => 2;
  
positive.code:   /**
     * The unique instance of this class.
     */
    static DynamicTypeImpl _INSTANCE = new DynamicTypeImpl._();
  
    /**
     * Return the unique instance of this class.
     */
    static DynamicTypeImpl get instance => _INSTANCE;
  
    /**
     * Prevent the creation of instances of this class.
  
negative.code:    * Constructor used by [CircularTypeImpl].
     */
    DynamicTypeImpl._circular()
        : super(instance.element, Keyword.DYNAMIC.syntax);
  
    @override
    int get hashCode => 1;
  