docs: function setTabIndex(elements) {
    for (let i = 0; i < elements.length; ++i) {
      if (elements[i].nodeName.toLowerCase() === "label" && elements[i].firstChild.nodeName.toLowerCase() === "input") {
        elements[i].firstChild.tabIndex = i;
      } else {
        elements[i].tabIndex = i;
      }
    }
  }