title: Python regular expression replace date
body: <p>I have string like this</p>
  
  <p><strong>INPUT:</strong></p>
  
  <pre><code>date = '2017-02-03 14:07:03.840'
  </code></pre>
  
  <p>And how replace <code>2017-02-03</code> In order to on output I'll have </p>
  
  <pre><code>2017-02-03 14:07:03.840 =&gt; 2015-01-01 14:07:03.840
  </code></pre>
  
  <p>How to replace only date without time? Using <strong>re</strong> module</p>