anchor.diff:                                (finish (line-end-offset line) start-symbol))
                                ((and (typep symbol 'literal-object-mixin))
                                 (finish (start-offset symbol) symbol
  -                                      (or (get-drawing-options highlighting-rules syntax symbol)
  +                                      (or symbol-drawing-options
                                             (make-drawing-options :function (object-drawer)))))
                                ((and (> (start-offset symbol) offset)
                                      (not (drawing-options-equal (or symbol-drawing-options
  
positive.code:      (defvar ,name (make-instance ',name))))
  
  (defclass lexeme (parser-symbol) ())
  
  (defmethod print-object ((lexeme lexeme) stream)
    (print-unreadable-object (lexeme stream :type t :identity t)
      (format stream "~s ~s" (start-offset lexeme) (end-offset lexeme))))
  
  (defclass nonterminal (parser-symbol) ())
  
  
negative.code: 
  (defun get-drawing-options (highlighting-rules syntax parse-symbol)
    "Get the drawing options with which `parse-symbol' should be
  drawn. If `parse-symbol' or the stack-top of syntax, return NIL."
    (when (and parse-symbol (not (eq (stack-top syntax) parse-symbol)))
      (funcall highlighting-rules syntax parse-symbol)))
  
  (defstruct (pump-state
  