App\services\Media::setTags PHP Method

    public function setTags($tags = [])
    {
        $this->tags = array_intersect((array) $tags, $this->allTags) ?: $this->allTags;
        // We always keep track of mtime.
        if (!in_array('mtime', $this->tags, true)) {
            $this->tags[] = 'mtime';
        }
    }