public long stamp() {
        long s = stamp;
        if (s == 0) {
            s = calculateStamp(partitions);
            stamp = s;
        }
        return s;
    }
@Test
    public void test_getStamp() throws Exception {
        InternalPartition[] partitions = createRandomPartitions();
        PartitionTableView table = new PartitionTableView(partitions);
        assertEquals(calculateStamp(partitions), table.stamp());
    }