code: protected function execute(InputInterface $input, OutputInterface $output)
      {
          if (!parent::execute($input, $output)) {
              return 1;
          }
  
          // If the self-test was called, immediately return
          if ($input->getOption('t') === true) {
              return 0;
          }
  
          \file_put_contents($this->config['pid'], \getmypid());
  
          $this->startProcessQueue();
      }
docs: Executes the command
  @param InputInterface $input
  @param OutputInterface $output
  @return void