title: Validating Regex US ZIP CODE with constraints in Python
body: <p>I'm trying to write a regex that follows these constraints:</p>
  <ul>
  <li>Exactly 5 digits</li>
  <li>Sometimes, but not always, followed by a dash with 4 more digits</li>
  <li>Zip code needs to be preceded by at least one whitespace</li>
  <li>Cannot be at the start of a text</li>
  </ul>
  <p>I've arrived at this but it's not giving me the output I want:</p>
  <pre><code>r&quot;^[A-Za-z].*\s.*\d{5}(?:[-\s]\d{4})?$&quot;
  </code></pre>