title: Split string into list of non-whitespace and whitespace
body: <p>I want to split a string into parts so that</p>
  
  <pre><code>Hello,  what   is up?
  </code></pre>
  
  <p>becomes</p>
  
  <pre><code>["Hello,", "  ", "what", "   ", "is", " ", "up?"]
  </code></pre>