code: Element consolidateMathMLNamespace(Element mathNode) throws MathConverterException {
          try {
              Document tempDoc;
              if (isNsAware(mathNode)) {
                  tempDoc = mathNode.getOwnerDocument();
              } else {
                  tempDoc = XMLHelper.string2Doc(XMLHelper.printDocument(mathNode), true);
              }
              // rename namespaces and set a new default namespace
              new XmlNamespaceTranslator()
                      .setDefaultNamespace(DEFAULT_NAMESPACE)
                      .addTranslation("m", "http://www.w3.org/1998/Math/MathML")
                      .addTranslation("mml", "http://www.w3.org/1998/Math/MathML")
                      .translateNamespaces(tempDoc, "");
              Element root = (Element) tempDoc.getFirstChild();
              removeAttribute(root, "xmlns:mml");
              removeAttribute(root, "xmlns:m");
  
              return root;
          } catch (Exception e) {
              logger.error("namespace consolidation failed", e);
              throw new MathConverterException("namespace consolidation failed");
          }
      }
docs: Should consolidate onto the default MathML namespace.
  
  @param mathNode root element of the document
  @return return the root element of a new document
  @throws MathConverterException namespace consolidation failed