[Chicken-users] Easy way to find if a variable is already defined?

[Sunnan]

Is there a (standard or chicken-specific) way to find out if a variable 
is already defined or not? Eg:

(defined? xyzzy)
-> #f
(define xyzzy (lambda () 'test))
(defined? xyzzy)
-> #t

I know that if one exists, it's not called defined.

This is easy enough to find out from the REPL or by catching an error, 
but I'm wondering if I'm missing something obvious.

What about other environment inspecting stuff? CL has lots of these, and 
I'm wondering if they're available for Chicken as well, or if I have to 
do without.