{% 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> {% else %} <!-- this is for the `when` statement --> <div class="header_logged_out"> Heya, why don't you <a href="/login">log in</a> or <a href="/signup">sign up</a>? </div> {% endmatch %} <hr /> {% else %} <!-- this is for whether or not the template has a user field or not --> {% endif %}