title: Django/Python models - multifield options
body: <p>Let's say I created a Model <code>AnObject</code>, and one of the fields would be <code>shape</code>. If I have 3 sets shape types that the model could be, circle, square, triangle. What is the best way to write out the model? Let us assume that these shapes are not models (so no foreignkey field should be used here) themselves, they are just shape types.</p>
  
  <pre><code>class AnObject(models.Model):
      shape = ?
  </code></pre>