anchor.diff:    (setf (config "externals.clasp.version") (getf argv :version))
     (cons t argv))
   
  +(defun externals-clasp-sentinel (argv)
  +  (with-open-file (i (merge-pathnames (format nil "lib/~A/~A/externals-clasp/~A/success" (uname-m) (uname) (getf argv :version))
  +                                      (homedir))
  +                     :direction :probe
  +                     :if-does-not-exist :create))
  +  (cons t argv))
  +
   (defun externals-clasp-help (argv)
     (format t "~%")
     (cons t argv))
  
positive.code:                 ,(decide-download 'externals-clasp-download)
                  externals-clasp-expand
                  externals-clasp-make
                  ))))
  
negative.code: 
  (defun externals-clasp-expand (argv)
    (format t "~%Extracting archive:~A~%" (opt "download.archive"))
    (when (and (probe-file (merge-pathnames (format nil "lib/~A/~A/externals-clasp/~A/success" (uname-m) (uname) (getf argv :version))
                                            (homedir)))
               (not (opt "install.force")))
      (format t "~A/~A is already installed. add 'install.force=t' option for the forced re-installation.~%"
  