How to construct subclasses of Immutable.Record?
<pre><code>class Event extends Immutable.Record {
  constructor(text) {
    super({text: text, timestamp: Date.now()});
  }
}
</code></pre>

<p>Calling <code>new Event()</code> seems to return a constuctor function:</p>

<pre><code>new Event('started').toString()
</code></pre>

<blockquote>
  <p>"function Record(values){ if(values instanceof RecordType){ return
  values;}</p>
  
  <p>if(!(this instanceof RecordType)){ return new RecordType(values);}</p>
  
  <p>if(!hasInitialized){ hasInitialized=true; var
  keys=Object.keys(defaultValues); setProps(RecordTypePrototype,keys);
  RecordTypePrototype.size=keys.length; RecordTypePrototype._name=name;
  RecordTypePrototype._keys=keys;
  RecordTypePrototype._defaultValues=defaultValues;}</p>
  
  <p>this._map=Map(values);}"</p>
</blockquote>

<p>Whereas calling the function returns the expected output:</p>

<pre><code>new Event('started')().toString()
</code></pre>

<blockquote>
  <p>"Record { "text": "started", "timestamp": 1453374580203 }"</p>
</blockquote>

<p>What am I doing wrong?</p>