+;;;###autoload
+(defun gnus-add-to-sorted-list (list num)
+ "Add NUM into sorted LIST by side effect."
+ (let* ((top (cons nil list))
+ (prev top))
+ (while (and list (< (car list) num))
+ (setq prev list
+ list (cdr list)))
+ (unless (eq (car list) num)
+ (setcdr prev (cons num list)))
+ (cdr top)))
+