title: python sort list of lists based on inner element AND ignore case
body: <p>let's say I have the following list in python</p>
  
  <pre><code>[ [1,"C"], [2, "D"], [3,"a"], [4,"b"] ]
  </code></pre>
  
  <p>I would like to sort the list by the letters so it would be </p>
  
  <pre><code>[ [3,"a"], [4,"b"], [1,"C"], [2, "D"] ]
  </code></pre>
  
  <p>To sort by the inner character, I would do <code>sorted(unsortedlist, key=itemgetter(1))</code>.<br>
  To sort by ignoring case, I would do <code>sorted(unsortedlist, key=str.lower)</code>.</p>
  
  <p>How do I sort by an inner element AND ignoring case at the same time?</p>