if (TF_GetCode(status) != TF_OK) return;
  if (childrens.size() > 1 || (childrens.size() == 1 && !childrens[0].empty()))
    return TF_SetStatus(status, TF_FAILED_PRECONDITION,
                        "Cannot delete a non-empty directory.");
  if (childrens.size() == 1 && childrens[0].empty()) {
    // This is the directory marker object. Delete it.
    std::string dir = path;
    MaybeAppendSlash(&dir);