title: Pythonic way to check if a variable was passed as kwargs?
body: <pre><code>visible = models.BooleanField()
  owner = models.ForeignKey(User, null=True)
  
  def update_address(**kwargs):
      address = Address.objects.get(address=kwargs.get('address'))
      try:
          address.visible = kwargs.get('visible')
      except:
          pass
      try:
          address.owner = kwargs.get('owner')
      except:
          pass
  </code></pre>
  
  <p><code>update_address()</code> should result in nothing happening to <code>address.visible</code> or <code>address.owner</code>.</p>
  
  <p><code>update_address(owner=None)</code> should delete whatever existing owner object was set.</p>
  
  <p>The thing that's confusing me is how to tell if <code>owner=None</code> was explicitly set so I know to delete the existing owner object, or if it was called without <code>owner</code> set to anything so I should leave the owner as it is.</p>