presto-parser/src/main/java/io/prestosql/sql/parser/AstBuilder.java/AstBuilder/aggregateResult
class AstBuilder:    @Override
    protected Node aggregateResult(Node aggregate, Node nextResult)
    {
        if (nextResult == null) {
            throw new UnsupportedOperationException("not yet implemented");
        }

        if (aggregate == null) {
            return nextResult;
        }

        throw new UnsupportedOperationException("not yet implemented");
    }