!7

p {
  new Map<Int, S> m;
  for (int n = 0; n <= 1024; n++) {
    if (n != 0) m.put(n*10, str(n*10));
    print("n=" + n); assertEquals(n, l(m));
    ArrayTreeMap<Int, S> map = new ArrayTreeMap(m);
    if (n <= 64) {
      printStruct(map);
      print("first=" + map.first());
    }
    assertEquals(n, l(map));
    for (int i : keys(m)) {
      assertEquals(str(i), map.get(i));
      assertNull(map.get(i-1));
      assertNull(map.get(i+1));
    }
    assertEquals(sorted(keys(m)), asList(keys(map)));
  }
  print("OK");
}

Began life as a copy of #1011276