Shortcodes

Let’s implement a 
[youtube] shortcode which embeds a youtube video.
For the desired usage of 
[youtube id=xxxx], we only need a few lines of code:
functions.php
// Should be called from within an init action hook
add_shortcode('youtube', 'youtube_shortcode');
function youtube_shortcode($atts)
{
    if (isset($atts['id'])) {
        $id = sanitize_text_field($atts['id']);
    } else {
        $id = false;
    }
    // This time we use Timber::compile since shortcodes should return the code
    return Timber::compile('youtube-short.twig', [
        'id' => $id,
    ]);
}
In youtube-short.twig we have the following template:
{% if id %}
	<iframe width="560" height="315" src="//www.youtube.com/embed/{{ id }}" frameborder="0" allowfullscreen></iframe>
{% endif %}
Now, when the YouTube embed code changes, we only need to edit the youtube-short.twig template. No need to search your PHP files for this one particular line.
Layouts with Shortcodes
Timber and Twig can process your shortcodes by using the 
{% apply shortcodes %} tag. Let’s say you're using a 
[tab] shortcode, for example:
{% apply shortcodes %}
    [tabs tab1="Tab 1 title" tab2="Tab 2 title" layout="horizontal" backgroundcolor="" inactivecolor=""]
        [tab id=1]
            Something something something
        [/tab]
        [tab id=2]
            Tab 2 content here
        [/tab]
    [/tabs]
{% endapply %}