presto-main/src/main/java/io/prestosql/sql/planner/planprinter/PlanPrinter.java/Visitor/visitSemiJoin
class Visitor:        @Override
        public Void visitSemiJoin(SemiJoinNode node, Void context)
        {
            NodeRepresentation nodeOutput = addNode(node,
                    "SemiJoin",
                    format("[%s = %s]%s",
                            node.getSourceJoinSymbol(),
                            node.getFilteringSourceJoinSymbol(),
                            formatHash(node.getSourceHashSymbol(), node.getFilteringSourceHashSymbol())));
            node.getDistributionType().ifPresent(distributionType -> nodeOutput.appendDetailsLine("Distribution: %s", distributionType));
            node.getSource().accept(this, context);
            node.getFilteringSource().accept(this, context);

            return null;
        }