title: Remove last 3 letters of string in Django template [:-3]
body: <p>I'm doing the following:</p>
  
  <pre><code>{% for wrapping in wrappings %}  //array of strings
  &lt;input type="radio" value="{{ wrapping[:-3] }}" etc
  </code></pre>
  
  <p>I want to output all the string in wrapping minus the last 3 letters but am recieving a:</p>
  
  <p><code>TemplateSyntaxError: Could not parse the remainder: '[:-3]' from 'wrapping[:-3]</code>.</p>
  
  <p>Any idea what's wrong/how to do this please?  Thanks,</p>