presto-main/src/main/java/io/prestosql/sql/planner/plan/RowNumberNode.java/RowNumberNode/getOutputSymbols
class RowNumberNode:    @Override
    public List<Symbol> getOutputSymbols()
    {
        return ImmutableList.copyOf(concat(source.getOutputSymbols(), ImmutableList.of(rowNumberSymbol)));
    }