anchor.diff:  
   (defgeneric allocate-buffer-storage (renderer size target usage))
   
  -(defclass renderer ()
  -  ((buffers :accessor buffers :initform nil)
  -   (bundles :accessor bundles :initform nil)
  -   (new-bundles :accessor new-bundles :initform nil)))
  -
   (defmethod allocate-buffer-storage ((renderer renderer) size target usage)
     (loop
        for buffer in (buffers renderer)
  
positive.code:                      :initform nil)
     (log :reader render-error-log :initarg :error-log :initform nil))
    (:report report-render-error))
  
  ;;; A simple reference counting protocol for objects that should do some
  ;;; cleanup e.g., release OpenGL resources, when they are no longer used.
  
negative.code: 
  (defgeneric draw (renderer))
  
  (defgeneric bind-state (renderer state))
  
  (defmethod bind-state ((renderer renderer) (state graphics-state))
    )
  
  (defun draw-render-groups (renderer)
    (upload-bundles renderer)
    (draw renderer))
  