If value in map (nested sights) doesn't exists nil will appear

[abcdw]

(->
 #:ih{:direction [:r3 :r4]
      :sights #:ihs {:translate {:b "str"}}
      :rules [{:r3 [:a :ihs/translate]
               :r4 [:o]}]
      :data {:r3 {:a :f}
             :r4 {:o "sr"}}}
 (assoc :ih/direction [:r4 :r3])
 ih/execute
 :ih/data)