(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]))