code: public void execute(TransformerImpl transformer)
              throws TransformerException
    {
  
  
  	try {
  
  		if (hasFallbackChildren()) {
  			executeFallbacks(transformer);
  		} else {
  			// do nothing
  		}
  		
  	} catch (TransformerException e) {
  		transformer.getErrorListener().fatalError(e);
  	}
    }
docs: Execute an unknown element.
  Execute fallback if fallback child exists or do nothing
  
  @param transformer non-null reference to the the current transform-time state.
  
  @throws TransformerException