What if you had this:

```jinja
<form action="post" method="example.com/something">
  <div>
    {{ browserid_button() }}
  </div>
</form>
```

The output of that would be (roughly):

```jinja
<form action="post" method="example.com/something">
  <div>
    <a href="#" class="browserid-button">
      <form action="post" method="example.com/browserid/login">
        <input type="hidden" name="assertion" />
      </form>
    </a>
  </div>
</form>
```

`.parents('form')` in that case would be `length==2`, right? (It's a horrible example but IMO worth using `closest` for considering how easy it is)