How to return and insert HTML code with a Twig function?

Question

I'm trying to add some images dynamically with Twig. So I defined a new Twig function called setImgService which basically chechs for a service name and depending on it, it will return some HTML code according to its image.

Function code:

$setImgService = new Twig_SimpleFunction('setImgService', function($serviceName){
    switch ($serviceName){
        case "Analitycs":
            return '<img src="assets/img/analitycs.png">';
        case "Hosting":
            return '<img src="assets/img/hosting.png">';
        case "SEO":
            return '<img src="assets/img/seo.png">';
        case "Maintenance":
            return '<img src="assets/img/maintenance.png">';
        case "Your own domain":
            return '<img src="assets/img/domain.png">';
        case "BackUp":
            return '<img src="assets/img/backup.png">';   
    }
});
// Add function to Twig
$twig->addFunction($setImgService);

But when I use

{{ setImgService('serviceName') }}

It returns HTML code like plain text.

Any help, please?