extractXmlChild function
Implementation
XmlElement? extractXmlChild(XmlElement elem, String name) {
  if (name == elem.localName) {
    return elem;
  }
  return elem.findElements(name).firstOrNull;
}XmlElement? extractXmlChild(XmlElement elem, String name) {
  if (name == elem.localName) {
    return elem;
  }
  return elem.findElements(name).firstOrNull;
}