title: Exclude rows that have empty cell
body: <p>I tried to exclude rows that have no 'UID'.
  I tried </p>
  
  <pre><code>temp = pd.read_csv(link)
  temp = temp[temp['UID'].notnull()]
  </code></pre>
  
  <p>It didn't work. I tried again,</p>
  
  <pre><code>temp = temp[temp['UID']!='null']
  </code></pre>
  
  <p>it didn't work either. </p>
  
  <p>here's the output in a form of jupyter notebook.</p>
  
  <p><a href="https://i.stack.imgur.com/vq04c.png" rel="nofollow noreferrer">screenshot of the output</a></p>