** evaluate references
   :PROPERTIES:
   :DATE:     2010-04-09
   :END:

#+begin_src emacs-lisp :var var=`(+ 9 ,(- 19 7)) :tangle yes
  (message "var is %S" var)
#+end_src

#+begin_src emacs-lisp
  (+ 1 2)
#+end_src

#+name:
: 3

#+begin_src ruby
  + 1 2
#+end_src

#+name:
: nil