Adding first/last/odd/even classes to a twig loop in Drupal 8

gistfile1.html.twig

{# Borrowed some syntax from https://gist.github.com/NikLP/cb9adc963036d1ffd8896928de2b9b7a and expanded upon it. #}
<div{{ attributes.addClass('container') }}>
  {% for item in items %}
    {# NB! notation: loop.index is 1 start, loop.index0 is zero start. #}
    
    {# Add first/last/odd/even classes to elements in loop #}
    {# odd/even #}
    {% set loopClasses = [] %}
    {% if loop.index is odd %}
      {% set loopClasses = loopClasses|merge(["odd"]) %}
    {% else %}
      {% set loopClasses = loopClasses|merge(["even"]) %}
    {% endif %}
    {# first #}
    {% if loop.first %}
      {% set loopClasses = loopClasses|merge(["first"]) %}
    {% endif %}
    {# last #}
    {% if loop.last %}
      {% set loopClasses = loopClasses|merge(["last"]) %}
    {% endif %}
    
    <div{{ item.attributes.addClass( loopClasses ) }}>{{ item.content }}</div>
  {% endfor %}
</div>