| type | since v1.7.28 | Edit | 
(HashSetIter. iter)(deftype HashSetIter [iter]
  Object
  (hasNext [_]
    (.hasNext iter))
  (next [_]
    (if ^boolean (.hasNext iter)
      (.-key (.next iter))
      (throw (js/Error. "No such element"))))
  (remove [_] (js/Error. "Unsupported operation")))