title: what does {variable_name} in an url pattern mean in Django?
body: <p>I'm reading Django Rest Framework documentation on router (<a href="https://www.django-rest-framework.org/api-guide/routers/" rel="nofollow noreferrer">https://www.django-rest-framework.org/api-guide/routers/</a>) and encounter this: </p>
  
  <pre><code>^accounts/{pk}/$
  </code></pre>
  
  <p>I understand ^ means start of line, $ means end of line and everything but {pk}. What does it mean?</p>