title: expected string or buffer
body: <p>I am writing a crawler which crawls and save the crawled information in variable <code>i</code>, so I did this:</p>
  
  <pre><code>my_string = i
  match = re.search("\&lt;!-- populate table from mysql database --&gt;(.*?)\&lt;/tbody&gt;" , my_string).group(1)    
  print match
  </code></pre>
  
  <p>Got this error:</p>
  
  <blockquote>
    <p>TypeError: expected string or buffer</p>
  </blockquote>
  
  <p>Can anyone give me advice on what's the problem here?</p>