title: SwfitUI-Value of type '[Course]' has no member 'identified'
body: <p>I am developing iphone app using xcode 11 beta 5.
  but I found the error like "Value of type '[Course]' has no member 'identified'"</p>
  
  <p>This is my source code.</p>
  
  <pre><code>struct ContentView: View {
  
      var body: some View {
          NavigationView{
              List(
                  [
                      Course.init(name: "sample1", imageUrl: "no image"),
                      Course.init(name: "sample2", imageUrl: "no image")
                  ].identified(by: \.name)
              ){
                  Text($0.name)
              }.navigationBarTitle(Text("Courses"))
          }
      }
  }
  </code></pre>
  
  <p>how can i solve this error?</p>