anchor.diff:    "Unloads and releases all shader resources."
     (with-slots ((vs vert-shader)
   	       (fs frag-shader)
  +	       (geo geo-shader)
   	       (program program)) this
   
       (when program
  
positive.code:     :initform nil)
     (vert-shader
      :reader vert-shader
      :initform nil)
     (attributes
      :reader attributes 
  
negative.code: 
    (with-slots ((vs vert-shader)
    	       (fs frag-shader)
  	       (geo geo-shader)
    	       (program program)) this
      (setf vs (gl:create-shader :vertex-shader))
      (setf fs (gl:create-shader :fragment-shader))    
  