anchor.diff:  	    data))
   
   (defmacro with-alu ((stream alu) &body body)
  -  #+clim `(with-drawing-options (,stream :ink ,alu) ,@body)
  -  #-clim `(let ((.old. (scl:send ,stream :char-aluf))
  -		(.new. #-clim (if (eq ,alu :draw) tv:alu-ior ,alu)
  -		       #+clim ,alu))
  -	    (unwind-protect
  -		(progn (scl:send-if-handles ,stream :set-char-aluf .new.) ,@body)
  -	      (scl:send-if-handles ,stream :set-char-aluf .old.))))
  +  `(with-drawing-options (,stream :ink ,alu) ,@body))
   
   (defmethod display-data ((self essential-graph-data-map-mixin) STREAM graph)
     "Display the data on graph GRAPH using DATUM-DISPLAYER."
  
positive.code: 
  (defmethod map-data ((dataset t) function (data sequence))
    "Map FUNCTION over each datum."
    #-(or sbcl cmu)
    (declare (downward-funarg function))
    (map nil function data))
  
  (defmethod map-data-xy ((dataset ESSENTIAL-GRAPH-DATA-MAP-MIXIN) function data)
    "Map function over each x y pair."
    #-(or sbcl cmu)
    (declare (downward-funarg function))
    (declare (compiled-function function))
    (map-data dataset
  	    #'(lambda (datum)
  		(declare (downward-function))
  
negative.code:   ;; hence the consing here.
    (list '("Line" :value :line) '("Line-Symbol" :value :line-symbol)))
  
  (defmethod transformation-offsets ((any t)) (values 0 0))
  
  (defmethod dont-record-output-history ((dataset t))
  