-;;; single LISTP call. Note that if SYMBOL is in the union, then LIST
-;;; will be a subtype even without there being any (member NIL). We
-;;; just drop through to the general code in this case, rather than
-;;; trying to optimize it.
+;;; single LISTP call. Note that if SYMBOL is in the union, then LIST
+;;; will be a subtype even without there being any (member NIL). We
+;;; currently just drop through to the general code in this case,
+;;; rather than trying to optimize it (but FIXME CSR 2004-04-05: it
+;;; wouldn't be hard to optimize it after all).