anchor.diff:    (princ (object-print-label (class-of object))
   	 stream))
   
  -(defmethod print-label ((object kilogram) stream)
  +(defmethod print-label ((object kilogram) (stream stream))
     "Print a KILOGRAM measurement in units of grams"
     (multiple-value-bind (mag boundp)
         (slot-value* object 'magnitude)
  
positive.code: 
  
  
  ;; (prefix-of (make-measurement 1 :m 24))
  ;; => #<PREFIX yotta (Y)>, 1
  ;;
  ;; (prefix-of (make-measurement 1 :m 23))
  ;; => #<PREFIX zetta (Z)>, 100
  ;;
  ;; (prefix-of (make-measurement 1 :m 22))
  ;; => #<PREFIX zetta (Z)>, 10
  ;;
  ;; (prefix-of (make-measurement 1 :m 21))
  ;; => #<PREFIX zetta (Z)>, 1
  ;;
  ;; (prefix-of (make-measurement 1 :m 3))
  ;; => #<PREFIX kilo (k)>, 1
  ;;
  ;; (prefix-of (make-measurement 1 :m -16))
  ;; => #<PREFIX atto (a)>, 100
  
  ;; Trivial decimal exponential mathematics, ad hoc syntax:
  
negative.code: ;; (object-print-label (find-prefix= 9))
  ;; => "G"
  
  (defmethod print-label ((object measurement) (stream stream))
    (multiple-value-bind (mag boundp)
        (slot-value* object 'magnitude)
      (cond 
  