(def inc-coll (partial map inc))
;;#'user/inc-coll
(inc-coll [4 5 6])
;;(5 6 7)
(def inc-coll-coll (partial map inc-coll))
;;#'user/inc-coll-coll
(inc-coll-coll [[1] [2]])
;;((2) (3))
(inc-coll-coll [[1] 3])
;;IllegalArgumentException Don't know how to create ISeq from: java.lang.Long  clojure.lang.RT.seqFrom (RT.java:542)

(defn inc2 [n]  (cond (sequential? n) (inc-coll n) (number? n) (inc n) :else n))
;;#'user/inc2

(def inc-coll-coll (partial map inc2))
;;#'user/inc-coll-coll
(inc-coll-coll [[1] [2]])
;;((2) (3))
(inc-coll-coll [[1] [2] 3])
;;((2) (3) 4)


;;without conditionals
(defmulti inc2 class)
;;#'user/inc2
(defmethod inc2 Number [n] (inc n))
;#object[clojure.lang.MultiFn 0x155f5b43 "clojure.lang.MultiFn@155f5b43"]
(inc2 10)
;11

(defmethod inc2 clojure.lang.Sequential [c] (map inc c))
;;#object[clojure.lang.MultiFn 0x155f5b43 "clojure.lang.MultiFn@155f5b43"]
(inc2 [1])
;(2)
(inc-coll-coll [[1] [2] 3])
;((2) (3) 4)