title: How add elapsed time to the list
body: <p>How can I add to the list every past half hour? that is, if now 20:59 I would like to have a conclusion like</p>
  
  <pre><code>['1:00', '1:30','2:00', ... , '20:00', '20:30']
  </code></pre>
  
  <p>how to add figured out every hour, but I can’t understand what to change in my case</p>
  
  <pre><code>time_list=['{}:00'.format(x) for x in range(8, datetime.datetime.now().hour + 1)]
  </code></pre>
  
  <p>result</p>
  
  <pre><code>['1:00', '2:00', ... , '19:00', '20:00']
  </code></pre>