title: What's exactly the difference between using strand::post and io_service::post with strand::wrap?
body: <p>In my understanding, posting handlers to a <code>strand</code> object means:</p>
  
  <ul>
  <li>Only one of the posted handlers is executed at a time.</li>
  <li>The handlers are invoked in order.</li>
  </ul>
  
  <p>Posting handlers directly to an <code>io_service</code> object and wrapping them by <code>strand::wrap</code> also means that only one of the posted handlers is executed at a time, but not in order.</p>
  
  <p>Is there any other difference? And how can I run two (or more) different kind of works (so, different handlers/functions) parallel (in different threads) by using <code>strand</code>?</p>