>  (match '(a ?? c) '(a f c))
()
>  (match '(?? a b c) '(a b c))
()
>  (match '(?? a b c) '(x g a b h a b c))
()
>  (match '(?? a b c ??) '(x d a b c i u a))
()
>  (match '(?? i ?v you ??) '(i think that i saw you yesterday))
((?v . saw))
>  (match '(a ?v (?v2 g h) ?? b) '(a c h u i b))
((?v2 . h) (?v . c))
>  (match '(?? a ??) '(a))
()
>  (match '(a ? c) '(a b c))
()
>  (match '(a ?va c) '(a b c))
((?va . b))
>  (match '(a (?v e f) c) '(a f c))
((?v . f))
>  (match '(a (?v e f) c) '(a g c))
fail
>  (match '(a (? e f) c) '(a f c))
()
>  (match '(a (? e f) c) '(a g c))
fail