code: public static boolean isValidSchematron (@Nullable final Node aNode)
    {
      if (aNode == null)
        return false;
  
      return isValidSchematron (TransformSourceFactory.create (aNode));
    }
docs: Check if the passed DOM node is a valid schematron instance.
  
  @param aNode
  The DOM node to check. May be <code>null</code>.
  @return <code>true</code> if the schematron is valid, <code>false</code>
  otherwise.