title: Prepend prefix to list elements with list comprehension
body: <p>Having a list like this:</p>
  
  <pre><code>['foo','spam','bar']
  </code></pre>
  
  <p>is it possible, using list comprehension, to obtain this list as result?</p>
  
  <pre><code>['foo','ok.foo', 'spam', 'ok.spam', 'bar', 'ok.bar']
  </code></pre>