presto-main/src/main/java/io/prestosql/sql/planner/optimizations/ActualProperties.java/ActualProperties/singleStreamPartition
class ActualProperties:        public static Global singleStreamPartition()
        {
            return partitionedOn(
                    SINGLE_DISTRIBUTION,
                    ImmutableList.of(),
                    Optional.of(ImmutableList.of()));
        }