assertEquals(-1, comp.compare(r1c2, r1c1));
assertEquals(-1, comp.compare(r2c2, r2c1));
assertEquals(1, comp.compare(r3c2, r3c1));
// get rid of old timestamps
comp.purge(0x10);
assertEquals(
"1:\n r120-0-1:r20-0-0 r130-0-1:r30-0-0\n" +
"2:\n r300-0-2:r30-0-0\n", comp.toString());
comp.purge(0x20);
assertEquals(