anchor.diff:                                     `(,l
                                        ,@(make-%= s (%=-place l)))))
       (? (has-return-value? l)
  -       (append (butlast x)
  -               (? (%=? l)
  -                  (? (wanted-return-value?)
  -                     (expex-guest-filter-setter l)
  -                     (make-return-value))
  -                  (make-%= s l)))
  +       (+ (butlast x)
  +          (? (%=? l)
  +             (? (wanted-return-value?)
  +                (expex-guest-filter-setter l)
  +                (make-return-value))
  +             (make-%= s l)))
          x)))
   
   (defun expex-body (x &optional (s '~%ret))
  
positive.code:   (expex-guest-filter-setter `(%= ,p ,(? (%=? v)
                                           (%=-place v)
                                           v))))
  
  (defun expex-add-var ()
    (funinfo-var-add *funinfo* (expex-sym)))
  
negative.code: 
  (defvar *expex* nil)
  
  
  ;;;; SHARED SETTER FILTER
  
  (defun %=-make-call-to-local-function (x)
    (with-%= place value x
      (expex-body (apply #'+ (frontend `((%= ,place (apply ,value. ,(compiled-list .value)))))))))
  
  (defun expex-compiled-funcall (x)
    (alet (%=-value x)
      (? (& (cons? !)
            (| (function-expr? !.)
               (funinfo-find *funinfo* !.)))
         (%=-make-call-to-local-function x)
         (list x))))
  
  
  ;;;; GUEST CALLBACKS
  