(shuffle coll)
Return a random permutation of coll
;; Make five permutations of the [1 2 3] vector.
;; Notice that the type of the shuffled collection is retained.
(repeatedly 5 (partial shuffle [1 2 3]))
;;=> ([2 3 1] [2 1 3] [2 3 1] [3 2 1] [3 1 2])