anchor.diff:  	       (set-attribute :selected "selected"))
   	(map (lambda (cell) 
   	       (with-slots (id cell-type) cell
  -		 (mirror! cell)
  +		 (setup-cell-mirror! cell)
   		 (when (= 'markup cell-type)
   		   (hide! (by-cell-id id ".CodeMirror")))))
   	     (notebook-cells *notebook*))))
  
positive.code: 	      (@ slider value) pos
  	      (@ (by-selector "#book-history-text") value) pos)
  	(hide! (by-selector ".book-title input"))
  	(set-page-hash (create :book id))))
  
      (defun notebook! (raw)
  
negative.code:     
      (defun dom-replace-cell (cell)
        (dom-replace (by-cell-id (@ cell id)) (cell-template cell))
        (setup-cell-mirror! cell))
  
      ;; CodeMirror and utilities
      (defun register-helpers (type object)
  