title: Coverting unicode codeepoint format
body: <p>Let's say that I have a character string containing bytes representing an emoji:</p>
  
  <pre><code>string &lt;- "This is a test. U+1F600"
  </code></pre>
  
  <p>How can I transform it into</p>
  
  <pre><code>string &lt;- "This is a test. \U0001F600"
  </code></pre>
  
  <p>So that I can render it as </p>
  
  <pre><code>utf8_print("This is a test \U0001F600")
  [1] "This is a test ​"
  </code></pre>