[O] LaTeX export with listings: unknown language "calc"

[Axel Kielhorn]

Hello!

I use some calc in my org document:

#+begin_SRC calc :var x=5 :var y=2 :exports both
  2 + a * x ** y
#+end_SRC 

When I export this to LaTeX the listings package complains about an unknown 
language calc.

To fix this I simply define a language:

#+LATEX_HEADER: \usepackage{listings}
#+LATEX_HEADER: \lstdefinelanguage{calc}{morekeywords={}}

Is this the correct way to do this?
Should this be added to the documentation?

Regards Axel