code: private Double extractTotalPrivate(XAttributable element) {
  		XAttribute attribute = element.getAttributes().get(KEY_TOTAL);
  		if (attribute == null) {
  			return null;
  		} else {
  			return ((XAttributeContinuous) attribute).getValue();
  		}
  	}
docs: /*
  Retrieves the total costs of an element, if set by this extension's total
  attribute.
  
  @param element Event to retrieve total costs for.
  
  @return The requested total costs.