title: Handling try and throws in Swift 3
body: <p>Before Swift 3 I was using:</p>
  
  <pre><code>guard let data = Data(contentsOf: url) else {
                  print("There was an error!)
                  return
              }
  </code></pre>
  
  <p>However I now have to use <code>do</code>, <code>try</code> and <code>catch</code>. I'm not familiar with this syntax. How would I replicate this behaviour?</p>