tree pretty printer in clojure - variation

gistfile1.clj

(defn print-tree
  ([tree]
     (print-tree tree ""))
  ([tree prefix]
     (apply str prefix (first tree) "\n"
            (map #(print-tree %1 (str prefix "\t")) (rest tree)))))

(deftest print-tree-test
  (is (= (print-tree
          '(parent
            (child1)
            (child2
             (grandchild1)
             (grandchild2)))
          "parent\n\tchild1\n\tchild2\n\t\tgrandchild1\n\t\tgrandchild2"))))