How do I check If not condition in Dust.js templates

dust.js

Solution

This is built into Dust, using the `^` tag (often called the "not" tag):

{^tags}
  <p>Sorry, There are no tags!</p>
{/tags}

Problem

How do I check for if not condition in the Dust.js templates? ``` {?tags} {:else} <p>Sorry, There are no tags!</p> {/tags} ```

Original source