<tr>
<th><a href="?sort_by={% if sort_by == "is_active" %}-{% endif %}is_active">active</a></th>
<th><a href="?sort_by={% if sort_by == "title" %}-{% endif %}title">title</a></th>
<tr>
<th><a href="?sort_by={% if sort_by == "is_active" %}-{% endif %}is_active">active</a></th>
<th><a href="?sort_by={% if sort_by == "title" %}-{% endif %}title">title</a></th>