Computing the value of some cells of a table using a named code block

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

Hello,

I have a table that summarizes my monthly budget, and I would like to
add a column where I compute my actual spending. I can get this
information using a shell script, but I don't know how to integrate it
in the table.

Here is a contrived example:
--8<---------------cut here---------------start------------->8---
#+name: spending
#+begin_src sh :var category="foo"
echo $category
#+end_src

| Category | Budget | Spending |
|----------+--------+----------|
| Food     |   1000 |          |
| Rent     |   1000 |          |
#+TBLFM: $3=call_spending("$1")
--8<---------------cut here---------------end--------------->8---

My question is: how do I write the TBLFM so that every cell of column
3 is the result of call the named block with column 1 as argument?

Thanks,

Alan