title: Download file using partial download (HTTP)
body: <p>Is there a way to download huge and still growing file over HTTP using the partial-download feature?</p>
  
  <p>It seems that this code downloads file from scratch every time it executed:</p>
  
  <pre><code>import urllib
  urllib.urlretrieve ("http://www.example.com/huge-growing-file", "huge-growing-file")
  </code></pre>
  
  <p>I'd like:</p>
  
  <ol>
  <li>To fetch just the newly-written data</li>
  <li>Download from scratch only if the source file becomes smaller (for example it has been rotated).</li>
  </ol>