presto-main/src/main/java/io/prestosql/sql/planner/planprinter/PlanPrinter.java/PlanPrinter/formatOutputs
class PlanPrinter:    private static String formatOutputs(TypeProvider types, Iterable<Symbol> outputs)
    {
        return Streams.stream(outputs)
                .map(input -> input + ":" + types.get(input).getDisplayName())
                .collect(Collectors.joining(", "));
    }