title: How to use ? and ?: and : in REGEX for Python?
body: <p>I understand that </p>
  
  <pre><code>* = "zero or more"
  ? = "zero or more" ...what's the difference?
  </code></pre>
  
  <p>Also, ?: &lt;&lt; my book uses this, it says its a "subtlety" but I don't know what exactly these do!</p>