presto-main/src/main/java/io/prestosql/util/GraphvizPrinter.java/NodePrinter/visitAssignUniqueId
class NodePrinter:        @Override
        public Void visitAssignUniqueId(AssignUniqueId node, Void context)
        {
            printNode(node, "AssignUniqueId", NODE_COLORS.get(NodeType.PROJECT));
            node.getSource().accept(this, context);

            return null;
        }