(rseq rev)
Returns, in constant time, a seq of the items in rev (which can be a vector or sorted-map), in reverse order. If rev is empty returns nil
user=> (vec (range 10))
[0 1 2 3 4 5 6 7 8 9]
user=> (rseq (vec (range 10)))
(9 8 7 6 5 4 3 2 1 0)
(rseq (into (sorted-map) {:a 1 :b 2}))
;; => ([:b 2] [:a 1])