title: Check if a variable is a date with Twig
body: <p>I have an array of variables that I want to display in a Twig template and each variable can be either a string or a date.</p>
  
  <p>If the variable is a date, I want to apply the <code>date</code> filter like this:</p>
  
  <pre><code>{{ my_var|date('d/m/Y') }}
  </code></pre>
  
  <p>And if it's a string I want it to display it the usual way:</p>
  
  <pre><code>{{ my_var }}
  </code></pre>
  
  <p>Is there any way to test if a variable is a date (ie. an instance of the PHP DateTime object)?</p>