code: private function registerSignals()
      {
          foreach ($this->signalHandler->getSignals() as $signal) {
              $this->logger->debug('Registering signal', [
                  'signal' => $signal
              ]);
  
              Loop::onSignal($signal, function ($signalId, $signal) {
                  $promise = $this->signalHandler->handle($signal);
                  $promise->onResolve(function ($error, $value) {
                      if ($error) {
                          $this->logger->info($error->getMessage());
                          return;
                      }
  
                      if ($value === null) {
                          $this->logger->info('Signal successfully handled. RPQ is now shutting down. Goodbye.');
                          exit(0);
                      }
                  });
              });
          }
  
          $this->setIsRunning(true);
      }
docs: Registers signals
  
  @return void