Lazy load images by default

Contao has some weird defaults, they are not as sane as I’d expect them to be. For instance, images should be lazy loaded by default. It took me some time to get to know how I’d add the loading="lazy" attribute to all of them. The docs have a section on how to customize html attributes. Contao seems to have a builtin twig function called attrs(). I still don’t know where this function comes from, I couldn’t locate the file myself and the docs won’t tell me.

{% use "@Contao/component/_picture.html.twig" %}
{% block image %}
    {% set img_attributes = attrs(img_attributes|default).set('loading', 'lazy') %}
    {{ parent() }}
{% endblock %}