presto-parser/src/main/java/io/prestosql/sql/tree/DefaultTraversalVisitor.java/DefaultTraversalVisitor/visitSelect
class DefaultTraversalVisitor:    @Override
    protected R visitSelect(Select node, C context)
    {
        for (SelectItem item : node.getSelectItems()) {
            process(item, context);
        }

        return null;
    }