title: change output format of chr to hexadecimal
body: <p>Suppose I have</p>
  
  <pre><code>print [chr 0x49, chr 0x9f]
  </code></pre>
  
  <p>which outputs</p>
  
  <pre><code>"I\159"
  </code></pre>
  
  <p>How do I make <code>print</code> use hexadecimal numbers when it prints characters that have to be shown as escape sequences? So that my output reads:</p>
  
  <pre><code>"I\x9f"
  </code></pre>