title: How do I sort a Ruby array of strings by length?
body: <p>How do I sort this:</p>
  
  <pre><code>arr = ["aaa","aa","aaaa","a","aaaaa"];
  </code></pre>
  
  <p>Into this?</p>
  
  <pre><code>arr = ["a","aa","aaa","aaaa","aaaaa"];
  </code></pre>