NetworkHandler* NetworkHandler::instance_ = nullptr;

  // ctor, dtor decl...

NetworkHandler* ZmqHandler::GetInstance() {
  if (instance_ == nullptr) {
    instance_ = new ZmqHandler();
  }
  return instance_;
}

void ZmqHandler::Start() {
  SetupNetworking();
  // fn body...
}

void ZmqHandler::SetupNetworking() {
  printf("Configuring ZMQ as network handler...\n");
  StartZmqServer();
}

void ZmqHandler::StartZmqServer() {
  printf("Starting ZMQ server...\n");
  // fn body...
}

void ZmqHandler::SendMessage(std::string message, Module module) {
  printf("Message sent to %s...\n", ModuleName(module).c_str());
  printf("Content: %s\n", message.c_str());
  // fn body...
}
}