(sorted? coll)
Returns true if coll implements Sorted
user=> (sorted? (sorted-set 5 3 1 2 4))
true
user=> (sorted? (sorted-map :a 1 :c 3 :b 2))
true
;; Note you can't just pass in a collection that happens to be sorted.
user=> (sorted? [1 2 3 4 5])
false
=> (sorted? (sort [1 2]))
false