presto-main/src/main/java/io/prestosql/sql/planner/OrderingScheme.java/OrderingScheme/fromOrderBy
class OrderingScheme:    public static OrderingScheme fromOrderBy(OrderBy orderBy)
    {
        return new OrderingScheme(
                orderBy.getSortItems().stream()
                        .map(SortItem::getSortKey)
                        .map(Symbol::from)
                        .collect(toImmutableList()),
                orderBy.getSortItems().stream()
                        .collect(toImmutableMap(sortItem -> Symbol.from(sortItem.getSortKey()), OrderingScheme::sortItemToSortOrder)));
    }