anchor.diff:                   initial-value
                    (scene-graph-frame-map scene-graph)))
   
  -  ;; (let ((value initial-value))
  -  ;;   (do-scene-graph-frames (frame scene-graph value)
  -  ;;     (setq value (funcall function value frame)))))
   
   (defun scene-graph-lookup (scene-graph frame-name)
     (tree-map-find (scene-graph-frame-map scene-graph)
                    frame-name))
   
  -  ;; (gethash frame-name (scene-graph-frame-map scene-graph)))
   
   ;; Find the relative transform of the scene frame
   (defgeneric scene-frame-tf (object))
  
positive.code:                (push mesh
                       (gethash (scene-mesh-file mesh) mesh-files))))
        ;; collect mesh files
        (do-scene-graph-frames (frame scene-graph)
          (loop
             for v in (scene-frame-visual frame)
             for g = (scene-visual-geometry v)
             when (and g (scene-mesh-p g))
             do (resolve-mesh g))))
      (maphash (lambda (mesh-file mesh-nodes)
                 (format *standard-output* "~&Converting ~A..." mesh-file)
                 (let* ((dom (dom-load mesh-file))
  
negative.code:              (visual (vis name)
                 (thing (scene-visual-pov vis (pov-transform* (pov-value (tf name)))))))
        ;; push frame geometry
        (do-scene-graph-visuals ((name vis) scene-graph)
          (visual vis name))
        ;; push frame transforms
        (when configuration-map
          (map nil #'thing
  