anchor.diff:  (in-package :pphtml)
  -
  -(defparameter *iota0*
  -  '(defun iota (n)
  -     (loop for i from 0 to (1- n) collect i)))
   
   (defun output-as-html (body &optional (out *standard-output*))
     (let ((format-string "<html><head><title> pretty print </title></head><body bgcolor=\"000000\" text=\"ffffff\"><p>~%~a~%</p></body></html>" ))
  
positive.code: (defun yellow (str)
    (color 255 255 0 str))
  
  ;;; I have no idea to dicretly utilize the pretty printed string.
  ;;; It's not a beautiful idea, but let me break the structure.
  ;;; Added nodes are marked by braces and removed nodes are marked
  ;;; by brackets.
  (defparameter *bracket-sample*
    '(defun iota (n [&optional (start 0)])
       (loop for i from {0} [start] upto (1- n) collect i)))
  
  (ql:quickload :cl-ppcre)
  (use-package :cl-ppcre)
  
  (defun pair-coloring (start end color-fn code)
    (regex-replace-all
      (create-scanner `(:sequence
  
negative.code:                     :single-line-mode t)
      (format nil "~a" code)
      (funcall color-fn "\\1")))
  