presto-parser/src/main/java/io/prestosql/sql/tree/DefaultTraversalVisitor.java/DefaultTraversalVisitor/visitExplain
class DefaultTraversalVisitor:    @Override
    protected R visitExplain(Explain node, C context)
    {
        process(node.getStatement(), context);

        for (ExplainOption option : node.getOptions()) {
            process(option, context);
        }

        return null;
    }