anchor.diff:       (%init-streamer
         (cepl.streams::init-buffer-stream-from-id
          %pre% (cepl.vaos:make-vao gpu-arrays nil)
  -       gpu-arrays nil 0 len t))
  +       gpu-arrays nil 0 len t draw-mode))
        (make-uninitialized-streamer)
        gpu-arrays)))
   
  
positive.code: 
      (setf (cepl.streams::buffer-stream-start streamer) new-start-pos
            (cepl.streams:buffer-stream-length streamer) c-len)
  
      (cepl.gpu-arrays::with-gpu-array-range-as-pointer
          (g-ptr g-arr new-start-pos c-len
  
negative.code:             (gpu-array-element-type arr)
              (first (gpu-array-dimensions arr)))))
  
  (defun make-buffer-streamer (dimensions element-type
                               &optional (draw-mode :triangles))
    (when (listp dimensions)
      (assert (= (length dimensions) 1)))
    (assert element-type)
    (assert (cepl.streams::valid-draw-mode-p draw-mode) (draw-mode))
    (let* ((len (first (ensure-list dimensions)))
           (array (make-gpu-array nil :element-type element-type
                                  :dimensions len
  