title: error: '...' is not a prefix unary operator
body: <p>Code:</p>
  
  <pre><code>let names = ["Anna", "Alex", "Brian", "Jack"]
  for name in names[...2] {
      print(name)
  }
  </code></pre>
  
  <p>Error:</p>
  
  <pre><code>Playground execution failed: error: MyPlayground.playground:3:19: error: '...' is not a prefix unary operator
  for name in names[...2] {
  </code></pre>
  
  <p>I am new to swift so any relevant link or any kind of help will be highly appreciated. Using swift 4</p>