presto-parser/src/main/java/io/prestosql/sql/tree/DefaultExpressionTraversalVisitor.java/DefaultExpressionTraversalVisitor/visitSubqueryExpression
class DefaultExpressionTraversalVisitor:    @Override
    protected R visitSubqueryExpression(SubqueryExpression node, C context)
    {
        // Don't traverse into Subqueries within an Expression
        return null;
    }