@(do
   (defun stream-positioned-to-right-place (name)
     (let* ((stream (open-file name "r+b"))
            (pre (progn (stream-set-prop stream :byte-oriented t)
                        (read-until-match #/@\(txr\)/ stream t))))
       (when (or (empty pre) (not (search-str pre "@(txr)")))
          (throwf 'error "~a isn't a TXR executable" name))
       stream)))
@(next :args)
@(cases)
-w
@string
@file
@  (eof)
@  (do
     (let ((f (stream-positioned-to-right-place file)))
       (with-in-string-byte-stream (s string)
         (mapdo (op put-byte @1 f)
                (take 127 (pad (gun (get-byte s)) 0)))
         (put-byte 0 f))))
@(or)
@file
@  (eof)
@  (do
     (let ((f (stream-positioned-to-right-place file)))
       (let ((arg-str (with-out-string-stream (u8)
                        (mapdo (op put-byte @1 u8)
                               (take 127 (gun (get-byte f)))))))
         (put-line arg-str))))
@(or)
@   (output)
usage: @{self-path} [-w string] txr-executable
@   (end)
@   (do (exit 1))
@(end)