presto-main/src/main/java/io/prestosql/util/GraphvizPrinter.java/GraphvizPrinter/visitWindow
class GraphvizPrinter:        @Override
        public Void visitWindow(WindowNode node, Void context)
        {
            printNode(node, "Window", format("partition by = %s|order by = %s",
                    Joiner.on(", ").join(node.getPartitionBy()),
                    node.getOrderingScheme()
                            .map(orderingScheme -> Joiner.on(", ").join(orderingScheme.getOrderBy()))
                            .orElse("")),
                    NODE_COLORS.get(NodeType.WINDOW));
            return node.getSource().accept(this, context);
        }