title: How to overcome error "look-behind requires fixed-width pattern" in Python?
body: <p>Could anyone tell me why this is not working in Python?</p>
  
  <pre><code>s = "conversion of hotel into 16no managed flats"
  re.sub("((?&lt;=\d\w|\w\d)|(?&lt;=\d))(\s*NO\.|NO\s)", " no ", s, re.IGNORECASE)
  </code></pre>
  
  <p>It's working in <code>https://regex101.com/</code> with Python engine selected.</p>
  
  <p>I've overcame the look-behind fix length issue but not quite.</p>