title: Twig filter included template
body: <p>I wanted to do something like this:</p>
  
  <pre><code>{{ include("tpl.html")|f }}
  </code></pre>
  
  <p>But that doesn't seem to work, it just printed <code>tpl.html</code> without any filtering, then I tried:</p>
  
  <pre><code>{% filter f %}
      {% include "tpl.html" %}
  {% endfilter %}
  </code></pre>
  
  <p>And it worked. I just wonder, why can't I use shorter one? Do I misunderstand something?
  Thanks in advance.</p>