title: Django raising 404 with a message
body: <p>I like to raise 404 with some error message at different places in the script eg: <code>Http404("some error msg: %s" %msg)</code>
  So, in my urls.py I included:</p>
  
  <pre><code>handler404 = Custom404.as_view()
  </code></pre>
  
  <p>Can anyone please tell me how should I be handling the error in my views. I'm fairly new to Django, so an example would help a lot.<br>
  Many thanks in advance.</p>