title: Writing my own event emitter fails
body: <p>I am trying to write an event emitter, based on <a href="https://howtonode.org/demystifying-events-in-node" rel="nofollow">this totorial</a>. 
  But the final event <code>on('cooked')</code> does not fire, why?</p>
  
  <pre><code>var events = require('events');
  
  function Dummy() {
      events.EventEmitter.call(this);
  }
  
  Dummy.super_ = events.EventEmitter;
  Dummy.prototype = Object.create(events.EventEmitter.prototype, {
      constructor: {
          value: Dummy,
          enumerable: false
      }
  });
  
  function _cook(a,cb) {
      console.log('frying it',a)
      cb(a)
  }
  
  Dummy.prototype.cooking = function(chicken) {
      var self = this;
      self.chicken = chicken;
      self.cook = _cook; // assume dummy function that'll do the cooking
      self.cook(chicken, function(cooked_chicken) {
          console.log('callback')
          self.chicken = cooked_chicken;
          self.emit('cooked', self.chicken);
      });
  
      return self;
  }
  
  var kenny = new Dummy();
  fried_chix = {type:'tasty'}
  
  var dinner = kenny.cooking(fried_chix);
  
  dinner.on('cooked', function(chicken) {
      console.log('we can eat now!')
  })
  </code></pre>