title: Chaining Filters together
body: <p>Given the following:</p>
  
  <pre><code>instances = Catalog.objects.filter(
                                  Q(imdb_url=imdb_url)
                                 |Q(isan=isan)
                                 |Q(amg_video_id=amg_video_id)
  )
  </code></pre>
  
  <p>How would I do the same in the following format, chaining each together:</p>
  
  <pre><code>instances = Catalog.objects.all()
  if imdb_url:
      instances = instances.filter(imdb_url = imdb_url) # OR
  if isan:
      instances = instances.filter(isan = isan) # OR
  if amg:
      instances = instances.filter(amg = amg) # OR
  </code></pre>
  
  <p>The above gives me the equivalent of:</p>
  
  <pre><code>instances = Catalog.objects.filter(imdb_url=imdb_url).filter(isan=isan).filter(amg=amg)
  </code></pre>
  
  <p>How would I do the eqivalent of the <code>Q</code> in the first query?</p>