code: static String getAttributeValue(Element element, String name) {
          Attr attribute = element.getAttributeNode(name);
          if (attribute == null) {
              return null;
          } else {
              return attribute.getValue();
          }
      }
docs: <p>Retutns the value of the named attribute of the given
  element. If there is no such attribute, returns null.</p>
  
  @param element element
  @param name    name
  @return value