How does one tell if something is a function?



What is a good way in Maxima (at the lisp level) to look at an input
and decide whether or not it is a function?  We need to make sure
something to be added to the finalevallist is a function, or bad things
happen, but I'm not sure how to check that something is indeed a
function.  

Thanks,
CY


		
__________________________________ 
Do you Yahoo!? 
Yahoo! Small Business - Try our new resources site!
http://smallbusiness.yahoo.com/resources/