func (annotatedStopPoint *XMLAnnotatedStopPointRef) LineRefs() []string {
    if len(annotatedStopPoint.lineRefs) == 0 {
        nodes := annotatedStopPoint.findNodes("LineRef")
        for _, node := range nodes {
            annotatedStopPoint.lineRefs = append(annotatedStopPoint.lineRefs, strings.TrimSpace(node.NativeNode().Content()))