prepareNodes method
      
void
prepareNodes(
    
    
- XmlElement xml
Implementation
void prepareNodes(XmlElement xml ) {
  final elements = xml.findAllElements( 'node' );
  // ensure all node elements have id attributes
  for (final element in elements) {
    if ( element.getAttribute( 'id' ) == null) {
      element.setAttribute( 'id', generateId() );
    }
  }
}