jone

(defun find-buildout-root (path)
  "Search PATH for a buildout root.

If a buildout root is found return the path, othwise return
nil."
  ;; find the most top one, not the first one
  (let ((dir default-directory)
        (previous nil))
    (while dir
      (let ((dir (find-parent-with-file dir "boostrap.py")))

jone

(defun jone-filter (condp lst)
  (delq nil
        (mapcar (lambda (x) (and (funcall condp x) x)) lst)))

(jone-filter (lambda (e) (string= e "hans")) ("hans" "peter"))