title: How to properly export an ES6 class in Node 4?
body: <p>I defined a class in a module:</p>
  
  <pre><code>"use strict";
  
  var AspectTypeModule = function() {};
  module.exports = AspectTypeModule;
  
  var AspectType = class AspectType {
      // ...    
  };
  
  module.export.AspectType = AspectType;
  </code></pre>
  
  <p>But I get the following error message:</p>
  
  <pre><code>TypeError: Cannot set property 'AspectType' of undefined
      at Object.&lt;anonymous&gt; (...\AspectType.js:30:26)
      at Module._compile (module.js:434:26)
      ....
  </code></pre>
  
  <p>How should I export this class and use it in another module? I have seen other SO questions, but I get other error messages when I try to implement their solutions.</p>