title: Multiple classes in single file
body: <p>I'm having trouble putting multiple classes into a single file. For example, when my file looks like:</p>
  
  <pre><code>public class FirstClass() {}
  public class SecondClass() {}
  public class ThirdClass() {}
  </code></pre>
  
  <p>I get an error during compilation. I'm not quite sure what's causing this. Any ideas?</p>