merge

(merge hmap1 hmap2)

(ns clojure.examples.example
   (:gen-class))
(defn example []
   (def demokeys (hash-map "z" 1 "b" 2 "a" 3))
   (def demokeys1 (hash-map "a" 2 "h" 5 "i" 7))
   (println (merge-with + demokeys demokeys1)))
(example)

{z 1, x 4, a 3, i 7, b 2, h 5}

• https://www.tutorialspoint.com/clojure/clojure_maps_merge.htm