title: I can't make the download progress bar from tqdm to show the progress
body: <p>I want to add a download progress bar with tqdm. The problem is that it shows me this :</p>
  
  <pre class="lang-sh prettyprint-override"><code>0%|                                                                           | 0/11535.92578125 [00:00&lt;?, ?KB/s]
  </code></pre>
  
  <p>And it downloads the file without showing a any progress. Here is my code:</p>
  
  <pre><code>s = requests.Session()
  r = s.post(url, login_data)
  response = s.get(link_to_pdf, stream=True)
  total_size = int(response.headers['content-length'])
  # download the pdf
  print(pdf_filename)
  with open(pdf_filename + '.pdf', 'wb') as f:
      for data in tqdm(iterable=response.iter_content(chunk_size=chunk_size), total=total_size/chunk_size, unit='KB'):
          f.write(response.content)
  </code></pre>