title: Convert different date formats to a given unique date format in python
body: <p>I have different date formats present as strings those are:</p>
  
  <pre><code>[ "2018-06-22",
  "June 22, 2018",
  "12/15/2017",
  "12-24-2015" ]
  </code></pre>
  
  <p>I want to convert them into a single yyyy-mm-dd ("2018-06-22") format. I can split and then do the reformatting but I am looking for a more better way. Thanks in advance!</p>