title: Differences between use of os.path.join and os.sep concatenation
body: <p>I am trying to figure out if it is better to use:</p>
  
  <pre><code>os.path.join(str1, str2)
  </code></pre>
  
  <p>or:</p>
  
  <pre><code>str1 + os.sep + str2
  </code></pre>
  
  <p>Profiling with <code>timeit</code> I found that, as expected, concatenation is faster:</p>
  
  <pre><code>%timeit 'playground' + os.sep + 'Text'
  10000000 loops, best of 3: 139 ns per loop
  
  %timeit os.path.join('playground', 'Text')
  1000000 loops, best of 3: 830 ns per loop
  </code></pre>
  
  <p>So my question is, since concatenation is also shorter, is there a reason to use <code>os.path.join(()</code>?</p>
  
  <p>Thanks</p>