title: Adding timestamp to file downloaded with urllib.urlretrieve
body: <p>I am using <code>urllib.urlretrieve</code> to download files, I would like to add something to check for changes before downloading. I already have something like the following:</p>
  
  <pre><code>import urllib
  
  urllib.urlretrieve("http://www.site1.com/file.txt", r"output/file1.txt")
  urllib.urlretrieve("http://www.site2.com/file.txt", r"output/file2.txt")
  </code></pre>
  
  <p>Ideally i would like the script to check for changes (compare the last modified stamp?), ignore if same and download if newer, I need the script to add a timestamp to the filename.</p>
  
  <p>Can anyone help?</p>
  
  <p>I am new to programming (python is my first) so any criticism welcome!</p>