presto-main/src/main/java/io/prestosql/util/GraphvizPrinter.java/NodePrinter/visitDistinctLimit
class NodePrinter:        @Override
        public Void visitDistinctLimit(DistinctLimitNode node, Void context)
        {
            printNode(node, format("DistinctLimit[%s]", node.getLimit()), NODE_COLORS.get(NodeType.LIMIT));
            return node.getSource().accept(this, context);
        }