title: Conditionally concatenating a list of strings with a condition
body: <p>I would appreciate suggestions for a more efficient way to conditionally concatenate a list.</p>
  
  <p>This technique seems to work:</p>
  
  <pre><code>sentence = ['this ','is ','are ','a ','sentence']
  string = ''
  for i in sentence:
      if i != 'are ':
          string += i
  </code></pre>