anchor.diff:  (defdynamic handler-frame)
   
   (defclass handler-frame ()
  -  (handlers
  -   parent-frame))
  +  (.handlers
  +   .parent-frame))
   
   (defun make-handler-frame ((handlers list))
     (let ((f (make handler-frame)))
  
positive.code:   (signal (make control-error)))
  
  (defclass handler ()
    (handler-class
     handler-function))
  
  (defun make-handler ((handler-class class) (handler-function function))
    (let ((h (make handler)))
  
negative.code:   (list-add list elt))
  
  (defclass list-iter () 
    (.list
     .i))
  
  (defun list-iter ((list list))
    (let ((iter (make list-iter)))
  