presto-parser/src/main/java/io/prestosql/sql/tree/DefaultTraversalVisitor.java/DefaultTraversalVisitor/visitSampledRelation
class DefaultTraversalVisitor:    @Override
    protected R visitSampledRelation(SampledRelation node, C context)
    {
        process(node.getRelation(), context);
        process(node.getSamplePercentage(), context);
        return null;
    }