title: Increment declared integer variable
body: <p>I try to do zebra striping:</p>
  
  <pre><code>{% set counter = 0 %}
  {% for entity in entities %}
    &lt;tr class="{{ cycle(['odd', 'even'], counter) }}"&gt;
      {% counter++ %}
  </code></pre>
  
  <p>but I am getting error:</p>
  
  <blockquote>
    <p>Unexpected tag name "counter" (expecting closing tag for the "for" tag
    defined near line 11)</p>
  </blockquote>
  
  <p>Could somebody give me solution?</p>
  
  <p><strong>[EDIT]</strong></p>
  
  <p>My bad solution is so easy:</p>
  
  <pre><code>{% set counter = counter + 1 %}
  </code></pre>