title: Using "and" and "or" operator with Python strings
body: <p>I don't understand the meaning of the line:</p>
  
  <pre><code>parameter and (" " + parameter) or ""
  </code></pre>
  
  <p>where <strong>parameter</strong> is string</p>
  
  <p>Why would one want to use <code>and</code> and <code>or</code> operator, in general, with python strings?</p>