anchor.diff:  
   (defgeneric draw-instruction (instruction stream))
     
  +(defmethod draw-instruction ((instruction typeq-instruction) stream)
  +  (format stream "   ~a [label = \"typeq ~a\"];~%"
  +	  (unique-id instruction)
  +	  (value-type instruction)))
  +
   (defmethod draw-instruction :around (instruction stream)
     (when (null (unique-id instruction))
       (setf (gethash instruction *instruction-table*) (gensym))
  
positive.code: 
  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  ;;;
  ;;; Draw instruction GET-ARGCOUNT-INSTRUCTION.
  
  (defmethod draw-instruction ((instruction get-argcount-instruction) stream)
    (format stream "   ~a [label = \"AC\", color = orange];~%"
  	  (unique-id instruction)))
  
  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  ;;;
  ;;; Draw instruction GET-ARG-INSTRUCTION.
  
  (defmethod draw-instruction ((instruction get-arg-instruction) stream)
    (format stream "   ~a [label = \"arg\", color = orange];~%"
  	  (unique-id instruction)))
  
  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  ;;;
  ;;; Draw instruction LOAD-CONSTANT-INSTRUCTION.
  
  (defmethod draw-instruction ((instruction load-constant-instruction) stream)
    (format stream "   ~a [label = \"LC ~d\"];~%"
  	  (unique-id instruction)
  	  (linkage-vector-index instruction)))
  
  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  ;;;
  ;;; Draw instruction LOAD-GLOBAL-INSTRUCTION.
  
  (defmethod draw-instruction ((instruction load-global-instruction) stream)
    (format stream "   ~a [label = \"LX ~d\"];~%"
  	  (unique-id instruction)
  	  (linkage-vector-index instruction)))
  
  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  ;;;
  ;;; Draw instruction CATCH-INSTRUCTION.
  
  (defmethod draw-instruction ((instruction catch-instruction) stream)
  
negative.code: 
  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  ;;;
  ;;; Drawing instructions.
  
  (defparameter *instruction-table* nil)
  