[plt-scheme] Swindle: defgeneric arity

I'm just getting my feet wet with Swindle, and noticed that you can't
have two methods with different arity on the same generic.  Is there a
deep implementation (or design) reason for this, or is this just
something left over from the CLOS tradition?

(I realize I can probably use the MOP to make multiple-arity generics,
but I'm not sure it's worth it...)

--dougorleans at gmail.com