title: Resume a webpage .read() with urlib
body: <p>Here is my code :</p>
  
  <pre><code>headers={'User-Agent': 'Mozilla/5.0'}
  req=Request(url,headers=headers)
  file=open(name,'wb')
  file.write(urlopen(req).read())
  file.close()
  </code></pre>
  
  <p>but when i get an exception and want to redownload the file i have to download from the begining ; and HTTPResponse don't have seek method . How can i resume my download ?
  Thank you !</p>