title: how to set displayName in a functional component [React]
body: <p>I know that setting the <code>displayName</code> is sometimes required especially when you're dealing with production builds. I want to know how to set it using my functional component - is it possible/allowed?</p>
  
  <p>Here's what I've got in my class component:</p>
  
  <pre class="lang-js prettyprint-override"><code>const MyComponent = React.createClass({
    displayName: 'HeyHey',
  
    render: function() {
      console.log(this.displayName);
    }
  });
  </code></pre>
  
  <p>How do I do the same thing inside a stateless component?</p>