    std::cout << std::setw(2) << std::setfill('0') << std::hex
              << static_cast<int>(c);
  }
#endif
  size_t send_result = sendto(fd_,
                              data_to_send.data(), data_to_send.size(),
                              0,
                              (struct sockaddr *) &gripper_sockaddr_,
                              sizeof(struct sockaddr_in));