Steel Bank Common Lisp

Hi,

I'm reading the step-by-step example on SBCL's ffi manual, the final  
line is "(free-alien res)" which I think is not necessary because the  
local foreign variable res will be disposed eventually. Am I right?

here's the link.  http://www.sbcl.org/manual/Step_002dBy_002dStep- 
Example-of-the-Foreign-Function-Interface.html#Step_002dBy_002dStep- 
Example-of-the-Foreign-Function-Interface


Cheers,
Jianshi