** inline expressions
   :PROPERTIES:
   :session:  'default
   :DATE:     2010-06-06
   :END:

#+begin_src R :exports code :results silent
  x<-4
#+end_src

the sum of 1 and x is equal to src_R{x+1}, now I'll sneakily reset
this value in a hidden inline block src_R[:exports none]{x<-2}, so
it's value is now src_R{x}.