anchor.diff:  (defun frame-name-compare (a b)
     (rope-compare-lexographic a b))
   
  +(defun frame-name-global-p (frame-name)
  +  (or (null frame-name)
  +      (zerop (length (rope-string frame-name)))))
  +
   (defstruct frame-inertial
     (mass 0d0 :type double-float)
     (inertia nil))
  
positive.code:       (make-mesh-data :vertex-vectors (vec-flatten verts)
                        :vertex-indices (fnvec-flatten indices)))))
  
  (defun scene-graph-pov-frame (scene-graph
                                &key
                                  render
  
negative.code:   (declare (type hash-table tf-absolute-map))
    (labels ((rec (frame-name)
               (cond
                 ((frame-name-global-p frame-name) ; global frame
                  (tf nil))
                 ((gethash frame-name tf-absolute-map) ; already in hash
                  (gethash frame-name tf-absolute-map))
  