anchor.diff:    (loop
       (incf point)
       (when (<= (length line-buffer) point)
  -      (return (length line-buffer)))
  +      (throw 'scan-error nil))
       (case (forward-syntax-type line-buffer point)
         ((:string-quote)
          (return (1+ point))))))
  
positive.code: (defun skip-expr-prefix-forward (line-buffer point)
    (skip-forward line-buffer point #'expr-prefix-char-p))
  
  (defun skip-list-forward (line-buffer point)
    (loop :with depth := 0 :do
      (incf point)
      (when (<= (length line-buffer) point)
        (return (length line-buffer)))
      (case (forward-syntax-type line-buffer point)
        ((:open-paren)
         (incf depth))
  
negative.code: 
  (defun backward-sexp-point (line-buffer point)
    (setq point (skip-space-backward line-buffer point))
    (or (catch 'scan-error
          (skip-sexp-backward line-buffer point))
        point))
  
  (defun backward-sexp (arg key)
    (setq rl:*point*
  