How do I chain babel blocks with arguments?

[Alan Schmitt <alan.schmitt@polytechnique.org>]

Hello,

I have several babel blocks that each work well, but I'm now trying to
chain them to build some bigger functionality out of them. I'm having
trouble finding out how to pass arguments between blocks. Here is
a small example:

--8<---------------cut here---------------start------------->8---
#+name: test1
#+begin_src emacs-lisp :var x="foo"
x
#+end_src

#+name:test2
#+begin_src emacs-lisp :var z="bar" :var y=test1(x=z)
y
#+end_src

#+call: test2(z="baz")
--8<---------------cut here---------------end--------------->8---

Unfortunately this does not work: the evaluation of block `test2' fails
by telling me `z' does not exist.

How can I execute block `test1' from block `test2' by passing an
argument that is one from test2?

Thanks,

Alan