anchor.diff:  (defmethod clpython:py-subs ((x amino::real-array) (item #+clpython-fixnum-is-a-class fixnum #-clpython-fixnum-is-a-class integer)) ;; tuple
     (aref (amino::real-array-data x) item))
   
  +(defmacro def-quat-attr (name index)
  +  `(def-attr-accessor ((object amino::real-array) ,name)
  +     (vecref object ,index)))
  +
  +(def-quat-attr |x| amino::+x+)
  +(def-quat-attr |y| amino::+y+)
  +(def-quat-attr |z| amino::+z+)
  +(def-quat-attr |w| amino::+w+)
  +
   ;;;;;;;;;;;;;;;;;;
   ;; Scene Graphs ;;
   ;;;;;;;;;;;;;;;;;;
  
positive.code: (defmethod clpython:py-subs ((scene robray::scene-graph) name)
    (robray::scene-graph-find scene name))
  
  (defmacro def-subs-accessors (type &body things)
    (with-gensyms (object name)
      `(defmethod clpython:py-subs ((,object ,type) ,name)
         (cond ,@(loop for (key function) in things
                    collect `((string= ,name ,key)
                              (,function ,object)))))))
  
  (def-subs-accessors robray::scene-frame
    ("name" robray::scene-frame-name)
  
negative.code: "
    (inverse x))
  
  ;;;;;;;;;;;;;;;;;
  ;;; Subscript ;;;
  ;;;;;;;;;;;;;;;;;
  