title: How to trim strings and list of strings in pandas column
body: <p>I have a df that looks like this:</p>
  
  <pre><code>0              ['AU06_threshold_h', 'AU12_threshold_h']  
  1                                     AU14_threshold_h   
  2                                     AU26_threshold_h   
  3                                                  NaN   
  4                                     AU01_threshold_h   
  </code></pre>
  
  <p>I want to trim the text from each string, as well as zeroes if the first character is a 0. It should look like this:</p>
  
  <pre><code>0              [6, 12]  
  1                   14 
  2                   26   
  3                  NaN   
  4                    1   
  </code></pre>
  
  <p>Please advise. Thank you!</p>