title: Extract text between double square brackets in Python
body: <p>If I have a string that may look like this:</p>
  
  <pre><code>"[[Category:Political culture]]\n\n          [[Category:Political ideologies]]\n\n"
  </code></pre>
  
  <p>How do I extract the categories and put them into a list?
  I'm having a hard time getting the regular expression to work.</p>