presto-orc/src/main/java/io/prestosql/orc/AbstractOrcDataSource.java/AbstractOrcDataSource/readLargeDiskRanges
class AbstractOrcDataSource:    private <K> Map<K, OrcDataReader> readLargeDiskRanges(Map<K, DiskRange> diskRanges)
    {
        if (diskRanges.isEmpty()) {
            return ImmutableMap.of();
        }

        ImmutableMap.Builder<K, OrcDataReader> slices = ImmutableMap.builder();
        for (Entry<K, DiskRange> entry : diskRanges.entrySet()) {
            DiskRange diskRange = entry.getValue();
            slices.put(entry.getKey(), new DiskOrcDataReader(diskRange));
        }
        return slices.build();
    }