src/language-css/utils.js/hasStringOrFunction
function hasStringOrFunction(groupList) {
  if (groupList && groupList.length) {
    for (let i = 0; i < groupList.length; i++) {
      if (groupList[i].type === "string" || groupList[i].type === "func") {
        return true;
      }
    }
  }
  return false;
}