presto-main/src/main/java/io/prestosql/execution/scheduler/AllAtOnceExecutionSchedule.java/AllAtOnceExecutionSchedule/visitSemiJoin
class AllAtOnceExecutionSchedule:        @Override
        public Void visitSemiJoin(SemiJoinNode node, Void context)
        {
            node.getFilteringSource().accept(this, context);
            node.getSource().accept(this, context);
            return null;
        }