presto-main/src/main/java/io/prestosql/sql/planner/iterative/rule/PruneOutputColumns.java/PruneOutputColumns/apply
class PruneOutputColumns:    @Override
    public Result apply(OutputNode outputNode, Captures captures, Context context)
    {
        return restrictChildOutputs(
                context.getIdAllocator(),
                outputNode,
                ImmutableSet.copyOf(outputNode.getOutputSymbols()))
                .map(Result::ofPlanNode)
                .orElse(Result.empty());
    }