int16_t send(const uavcan::CanFrame& frame, uavcan::MonotonicTime tx_deadline, uavcan::CanIOFlags flags) override
 {
     std::lock_guard<std::mutex> lock(mutex_);
     prioritized_tx_queue_.push(frame, tx_deadline, uavcan::CanTxQueue::Volatile, flags);
     return 1;
 }