title: How to use Jijna2 unique filter
body: <p>I'm trying to only display unique results through jinja for loop. I have</p>
  
  <pre><code>{% for i in items %}
      {{ i.item_name | unique }}
  {% endfor %}
  </code></pre>
  
  <p>I receive this error: <strong>jinja2.exceptions.TemplateAssertionError: no filter named 'unique'</strong>. Any help will be appreciated.</p>