(fnext x)
Same as (first (next x))
user=> (fnext ['(a b c) '(b a c)]) (b a c) user=> (fnext '([a b c] [b a c])) [b a c] user=> (fnext {:a 1 :b 2 :c 3}) [:b 2] user=> (fnext []) nil user=> (fnext [1]) nil