anchor.diff:                            &rest args
                             &key (comment nil)
                             (filter (constantly t))
  -                          &allow-other-keys)
  +			  &allow-other-keys)
     (let ((data-set (make-instance 'plot-data-set
                       :comment comment
                       :style (plot-kind->plot-style plot-kind)))
  
positive.code:        (when (funcall filter datum)  
           (insert-item (data data-set) 
                        (apply #'make-data-point point-kind datum args)))))
      (values data-set)))
  
  (defmethod make-data-point ((point-kind (eql :box)) datum
  
negative.code:        (apply #'make-plot plot-kind
                    (collect-elements
                     data
                     :filter (lambda (e) 
  			     (funcall test data-kind (funcall key e))))
                    :x-coord x-coord
                    :y-coord y-coord
                    :plot plot
                    :legend (when legend-creator
  			    (funcall legend-creator data-kind))
                    args)))
      (values plot)))
  
  (defun scatter-plot (data &rest args &key
  