GROQ custom function

custom_fn.groq

fn utils::expandLink($lang) = $lang[]{
    ...,
    markDefs[]{
      ...,
      _type == "internalLink" => {
        "slug": @.reference->number,
        "type": @.reference->_type,
      }
    }
  };
  
*[_type == "title"]{
  ...,
  desc {
      "de": utils::expandLink(de),
      "fr": utils::expandLink(fr),
  }
}