(defun join-string2 (string-list &key (join-by " ") (convert-to-string nil))
  (declare (ignorable convert-to-string))
  (let ((length-1 (1- (length string-list))))
    (with-output-to-string (s)
      (dolist (word (subseq string-list 0 length-1))
        (princ word s) (princ join-by s))
      (princ (nth length-1 string-list) s)
      s)))