title: Django User model, adding function
body: <p>I want to add a new function to the default User model of Django for retrieveing a related list of Model type.</p>
  
  <p>Such Foo model:</p>
  
  <pre><code>class Foo(models.Model):
      owner = models.ForeignKey(User, related_name="owner")
      likes = models.ForeignKey(User, related_name="likes")
  </code></pre>
  
  <p>........</p>
  
  <pre><code>    #at some view
      user = request.user
      foos= user.get_related_foo_models()
  </code></pre>
  
  <p>How can this be achieved?</p>