title: python - how can I round a datetime object to the most recent previous quarter hour?
body: <p>Let say I have datetime objects.  I would like them rounded to the nearest preceding quarter hour:</p>
  
  <pre><code>2014-07-18T14:23:12 --&gt; 2014-07-18T14:15:00
  2014-07-18T14:14:59 --&gt; 2014-07-18T14:00:00
  2014-07-18T00:00:00 --&gt; 2014-07-18T00:00:00
  </code></pre>
  
  <p>Etc.</p>