[O] Getting rid of the #+begin_example #+end_example in src blocks evaluation

[Julien Cubizolles]

I'm trying to create a list of entries with timeshifts. I found this
very nice example:

#+begin_src emacs-lisp
(with-temp-buffer
  (insert "*** Cours
<2014-09-07 lun 8:45-12:00>")
  (goto-char (point-min))
  (org-clone-subtree-with-time-shift 30 "+1w")
  ;; ignore this
  (let ((str (buffer-string)))
     (set-text-properties 0 (length str) nil str) str))
#+end_src

but the results is bracketed by a

#+begin_example
*** Cours....
#+end_example

which can of course very easily be removed. Is there a way to get only
the headings ?

Julien.