user=>
 (defn word-enrichment
  "input:  a string 'a b b'
   output: a map : {'a' 1 'b' 2}"
  [str_in]
  {:pre [(= (type str_in) (type ""))]}
  (let [all (clojure.string/split str_in #"\b+")]
    (reduce
      #(let [v (%1 %2)]
         (assoc %1 %2
            (if v (inc v) 1) )) {} all)))