This is a sample of a custom Twig filter. It was built to replace a View that was not playing nice, and rather than spend time fixing the view, I was curious how I could pass the data to Twig directly. Of course the front end guy already set up the page in css so the returned data is formatted for it.
This is not for your site, nor really for any public implementation. It is really just for me to see how to build Twig filters...
In a twig file I put {{ product | mfr_list }} to call the return list. As of this I am not working with the variable being passed.
any questions ping me on Twitter @michalsen