title: Split string into groups of 3 characters
body: <p>I have a string</p>
  
  <pre><code>ddffjh3gs
  </code></pre>
  
  <p>I want to convert it into a list</p>
  
  <pre><code>["ddf", "fjh", "3gs"]
  </code></pre>
  
  <p>In groups of 3 characters as seen above.
  What is the best way to do this in python 2.7?</p>