filesystem "/mnt/btrfs";

k = key(BTRFS_DEV_TREE_OBJECTID, BTRFS_ROOT_ITEM_KEY, 0, 0);
res = search(BTRFS_ROOT_TREE_OBJECTID, k);

i = 0;
for v in res {
  if i == 3 {
    break;
  }

  print res[i];

  i += 1;
}