title: Python .join or string concatenation
body: <p>I realise that if you have an iterable you should always use <code>.join(iterable)</code> instead of <code>for x in y: str += x</code>. But if there's only a fixed number of variables that aren't already in an iterable, is using <code>.join()</code> still the recommended way?</p>
  
  <p>For example I have</p>
  
  <pre><code>user = 'username'
  host = 'host'
  </code></pre>
  
  <p>should I do</p>
  
  <pre><code>ret = user + '@' + host
  </code></pre>
  
  <p>or</p>
  
  <pre><code>ret = '@'.join([user, host])
  </code></pre>
  
  <p>I'm not so much asking from a performance point of view, since both will be pretty trivial. But I've read people on here say always use <code>.join()</code> and I was wondering if there's any particular reason for that or if it's just generally a good idea to use <code>.join()</code>.</p>