anchor.diff:    (argument-expand fun def nil :apply-values? nil))
   
   (fn argument-expand-values (fun def vals &key (break-on-errors? t))
  -  (@ [? (argument-synonym? _)
  -        ._
  -        _]
  -     (cdrlist (argument-expand fun def vals :break-on-errors? break-on-errors?))))
  +  (mapcar [? (argument-synonym? _)
  +             ._
  +             _]
  +          (cdrlist (argument-expand fun def vals :break-on-errors? break-on-errors?))))
  
positive.code:                                              apply-values?
                                               concatenate-sublists?
                                               break-on-errors?)
                             (exp-main .def .vals))
                     (. (. nil (argument-expand-0 fun def. vals.
                                                  apply-values?
                                                  concatenate-sublists?
  
negative.code:      (!= (exp-main argdefs alst)
         (? (eq ! 'error)
            !
            (nconc ! (nconc (mapcar [. _. (. '%key ._)] key-args) rest-arg))))))
  
  (fn argument-expand (fun def vals &key (apply-values? t)
                                         (concatenate-sublists? t)
  