title: if... !true conditional rendering in nunjucks
body: <p><code>if...true</code> conditionals work like a charm as <a href="https://mozilla.github.io/nunjucks/templating.html#if" rel="noreferrer">outlined here</a> in the docs.</p>
  
  <p>but if I try to do something like:</p>
  
  <pre><code>{% if !posts.length %}
  &lt;i&gt;No project posts yet!&lt;/i&gt;
  {% endif %}
  </code></pre>
  
  <p>I get an error:</p>
  
  <pre><code>Template render error: (/home/nak/clones/mf3/views/project.html) [Line 10, Column 9]
   unexpected token: !
  </code></pre>
  
  <p>I've worked around this by doing:</p>
  
  <pre><code>{% if posts.length %}
  {% else %}
  &lt;i&gt;No project posts yet!&lt;/i&gt;
  {% endif %}
  </code></pre>
  
  <p>Is there a better (correct) way to do this?</p>