(defn list-item
  ;; three arguments
  ([class content href]
   ;; define an <a> inside the list
   [:li {:class class}
        [:a (merge {:href href}
                   (when (= "osx" client)
                     {:target "_blank"})) content]])
  ;; two arguments
  ([class content]
   ;;will only define a list item
   [:li {:class class} content]))