   func start() {
     print("Start polling")
     active = true
-    dispatch_async(isoloationQueue) {
+    dispatch_async(isolationQueue) {
       self.makeRequest()
     }
   }

    if active {
      callback("\(NSDate())")
      let dispatchTime = dispatch_time(DISPATCH_TIME_NOW, Int64(Double(NSEC_PER_SEC) * 1))
      dispatch_after(dispatchTime, isoloationQueue) {
        self.makeRequest()
      }
    }

class Pollster {
  let callback: (String) -> ()
  private var active: Bool = false
  private let isolationQueue = dispatch_queue_create("com.raywenderlich.pollster.isolation", DISPATCH_QUEUE_SERIAL)
  
  init(callback: (String) -> ()) {
    self.callback = callback
