title: Is socket.io emit callback appropriate?
body: <p>Recently I have been messing around with socket.io and found this interesting thing, that I can have emit function callback like this.</p>
  
  <p>I start emitting on client side like this:</p>
  
  <pre><code>client.emit('eventToEmit', dataToEmit, function(error, message){
      console.log(error);
      console.log(message);
  });
  </code></pre>
  
  <p>Then I can fire a callback from server-side like this:</p>
  
  <pre><code>client.on('eventToEmit', function(data, callback){
      console.log(data);
      callback('error', 'message');
  });
  </code></pre>
  
  <p>Everything works fine with no errors, but I am interested if doing something like this is appropriate since I have not seen anything similar in the documentation or any example so far.</p>