anchor.diff:  (defun graphviz-export-to-file (fsa file) 
     "This function will write the dot description of the FSA in the stream."
     (let ((p (open-output-file file)))
  -    (display (format "digraph G {~%  rankdir = LR;~%  size = \"8, 10\";~%") 
  -	     p)
  +    (format p "digraph G {~%  rankdir = LR;~%  size = \"8, 10\";~%") 
       (if (not (null? (fsa-builder-finals fsa)))
   	(progn
  -	  (display (format "~%  node (shape = doublecircle);~% ")
  -		   p)
  +	  (format p "~%  node (shape = doublecircle);~% ")
   	  (map (lambda (x) 
  -		 (display (format " \"~A\"" (node-label x))
  -			  p))
  +		 (format p " \"~A\"" (node-label x)))
   	       (fsa-builder-finals fsa))
  -	  (display ";")))
  -    (display (format "~%~%  node (shape = circle);~% ")
  -	     p)
  +	  (foramt p ";")))
  +    (format p "~%~%  node (shape = circle);~% ")
       (map (lambda (label)
  -	   (display (format " \"~A\"" label)
  -		    p))
  +	   (format p " \"~A\"" label))
   	 (hash-table-keys (fsa-builder-nodes fsa)))
  -    (display (format ";~%~%")
  -	     p)
  +    (format p ";~%~%")
       (map (lambda (node)
   	   (map (lambda (edge)
  -		  (display (format "  \"~A\" -> \"~A\" (label = \"~A\");~%"
  -				   (car edge)
  -				   (caddr edge)
  -				   (if (null? (cadr edge))
  -				       "epsilon"
  -				     (cadr edge)))
  -			   p))
  +		  (format p 
  +			  "  \"~A\" -> \"~A\" (label = \"~A\");~%"
  +			  (car edge)
  +			  (caddr edge)
  +			  (if (null? (cadr edge))
  +			      "epsilon"
  +			    (cadr edge))))
   		(node-edges node)))
   	 (hash-table-values (fsa-builder-nodes fsa)))
  -    (display (format "}~%") 
  -	     p)
  +    (format p "}~%") 
       (close-output-port p)
       fsa))
   
  
positive.code:     fsa))
  
  (defun fsa-remove-edge! (fsa src-label input-symbol dst-label)
    (let ((src-node (hash-table-ref/default (fsa-builder-nodes fsa) src-label #f))
  	(dst-node (hash-table-ref/default (fsa-builder-nodes fsa) dst-label #f)))
      (if (and src-node dst-node)
  	(node-remove-edge! src-node input-symbol dst-node))
      fsa))
  
negative.code: 				   (setf nodes (cons (car n) nodes))
  				   (retreive-nodes (append (cdr n) (lset-difference eq
  										    (node-destinations (car n))
  										    nodes))))))
  	       (build-fsa-builder-with-nodes
  		(lambda ()
  		  (for-each (lambda (node)
  			      (fsa-add-node! fsa-builder node))
  			    nodes))))
  	      (retreive-nodes nodes))
        fsa-builder))
  
  