title: change the order of string in python
body: <p>How do I change the sequence of string?
  For e.g. </p>
  
  <pre><code>mys='4002-10-21'
  </code></pre>
  
  <p>Expected result:</p>
  
  <pre><code>'4002-21-10'
  </code></pre>
  
  <p>What I have tried:</p>
  
  <p>I can enumerate the splitted string and then re-arrange the sequence like 1-3-2</p>
  
  <pre><code>newlist=list()
  for i, v in enumerate(mys.split('-')):
      newlist.append(v)
  </code></pre>