{% if self.has_optional_user() %}

{% match user %}
{% when Some with (usr) %}
<div class="header_logged_in">
    Hello, {{ usr.username }}!
    <div>
        <form action="/logout" enctype="application/x-www-form-urlencoded" method="post">
            <button>
                <input type="submit" value="sign out?" class="warning">
            </button>
        </form>
    </div>
</div>

{% when None %}
<div class="header_logged_out">
    <a href="/login">log in</a> or <a href="/signup">sign up</a>?
</div>
{% endmatch %}

{% else %} <!-- this is for whether or not the template has a user field or not -->

{% endif %}