title: How do I slice a string every 3 indices?
body: <p>I'm using Python to program for the lab I work at. How can I slice out every 3 characters in a given string and append it to a list?</p>
  
  <p>i.e. XXXxxxXXXxxxXXXxxxXXXxxxXXX (where X or x is any given letter)</p>
  
  <pre><code>string = 'XXXxxxXXXxxxXXXxxxXXXxxxXXX'
  mylist = []
  
  for x in string:
      string[?:?:?]
      mylist.append(string)
  </code></pre>
  
  <p>I want the list to look like this: ['XXX','xxx','XXX','xxx','XXX'....etc]</p>
  
  <p>Any ideas?</p>