(= call-stack* (thread-local))
  (= (call-stack*) (list))

  (let old-fn fn
    (mac fn (args . body)
      (w/uniq (name ret)
        `(,old-fn ,args
            (push (list ,name ,body) (call-stack*))
             (let ,ret (do ,@body)
              (pop  (call-stack*))
               ,ret)))))