anchor.diff:  		  (unless (equalp (third res-fact) res)
   		    (when res-fact (delete! book res-fact))
   		    (insert! book (list cell-id :result res)))))))
  -      (write-delta! book))))
  +      (write! book))))
   
   (defmethod empty-expression? ((contents string))
     (when (cl-ppcre:scan "^[ \n\t\r]*$" contents) t))
  
positive.code: 		 (delete! book val-fact)
  		 (insert! book (list cell-id :result res))
  		 (delete! book (list cell-id :stale t))
  		 (write-delta! book))
  	       (publish! :cl-notebook-updates 
  			 (update :book (notebook-name book) 
  				 :cell cell-id 
  
negative.code: 
  (define-json-handler (cl-notebook/notebook/new-cell) ((book :notebook) (cell-language :keyword) (cell-type :keyword))
    (let ((cell-id (new-cell! book :cell-type cell-type :cell-language cell-language)))
      (write! book)
      (publish! 
       :cl-notebook-updates 
       (update :book (notebook-name book) :action 'new-cell :cell-id cell-id 
  