(subtypep '(function)
'(function (t &rest t))))
'(nil t)))
-#+nil
(assert (and (subtypep 'function '(function))
(subtypep '(function) 'function)))
'(cons single-float single-float))))
(assert (subtypep '(cons integer single-float)
'(or (cons fixnum single-float) (cons bignum single-float))))
+
+(assert (not (nth-value 1 (subtypep '(and null some-unknown-type)
+ 'another-unknown-type))))