title: How to suppress compiler warning
body: <p>this code:</p>
  
  <pre><code>guard let isNotNil = anOptional
          else {
              #if DEBUG
                  fatalError()
              #endif
              return false
      }
  </code></pre>
  
  <p>gives a compiler warning when in debug mode on <code>return false</code>:</p>
  
  <blockquote>
    <p>Will never been executed</p>
  </blockquote>
  
  <p>Which is right but by intention.</p>
  
  <p>How can I suppress this warning?</p>