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1. JSON deserialization in guard

   guard let data = optionalData,
      optionalDict = try? NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers) as? [String:AnyObject],
      d = optionalDict,
      latestVersionString = d["latest_version_string"] as? String,
      latestVersionURL = d["latest_version_url"] as? String else {
      return
   }