How to do a for loop in Twig PHP

It was funny I had to look up this one because it is one I have already done a lot of times. Yet, again I had to look it up. 

This is the way to do a "for" loop. We are going to loop over an array of Node objects of type 'sector'

Solution

{% for sector in sectors %}
  <a class="btn btn-primary" href="#{{ sector.id() }}">{{ sector.label() }}</a>
{% endfor %}