title: Setting element of array from Twig
body: <p>How can I set member of an already existing array from Twig?</p>
  
  <p>I tried doing it next way:</p>
  
  <pre><code>{% set arr['element'] = 'value' %}
  </code></pre>
  
  <p>but I got the following error:</p>
  
  <blockquote>
    <p>Unexpected token "punctuation" of value "[" ("end of statement block"
    expected) in ...</p>
  </blockquote>