title: Adding a case to an existing enum with a protocol
body: <p>I want to create a <code>protocol</code> that enforces a certain case on all <code>enums</code> conforming to this <code>protocol</code>. </p>
  
  <p>For example, if I have a <code>enum</code> like this:</p>
  
  <pre><code>enum Foo{
      case bar(baz: String)
      case baz(bar: String)
  }
  </code></pre>
  
  <p>I want to extend it with a <code>protocol</code> that adds another case:</p>
  
  <pre><code>case Fuzz(Int)
  </code></pre>
  
  <p>Is this possible?</p>