title: TypeError: sequence item 1: expected string, tuple found
body: <p>I want to write the content of html </p>
  
  <pre><code>html = ' '.join(html)
      html_file = open(diff_path, "w")
      html_file.write(html)
      html_file.close()
  </code></pre>
  
  <p>but i'm getting this error on the first line shared although <code>html = ' '.join(html)</code> should have fixed that.</p>
  
  <pre><code>typeError: sequence item 1: expected string, tuple found
  </code></pre>
  
  <p>how can i fix it?</p>