Clojure映射merge

(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)