code: public static MathNode generateMathNode(CMMLInfo cmmlInfo) throws MathNodeException {
          Objects.requireNonNull(cmmlInfo, "cmml document is null");
          try {
              return generateMathNode(CMMLHelper.getFirstApplyNode(cmmlInfo));
          } catch (XPathExpressionException e) {
              logger.error("could not generate math node tree", e);
              throw new MathNodeException("could not generate math node tree", e);
          }
      }
docs: Create a math expression tree (MEXT) starting from an CMMLInfo document.
  
  @param cmmlInfo CMMLInfo document
  @return first MathNode representing the root of the MEXT, or null