Monolog\Logger::pushProcessor PHP Method

    public function pushProcessor($callback)
    {
        if (!is_callable($callback)) {
            throw new \InvalidArgumentException('Processors must be valid callables (callback or object with an __invoke method), '.var_export($callback, true).' given');
        }
        array_unshift($this->processors, $callback);
    }

 /**
  * {@inheritDoc}
  */
 public function register(Container $container)
 {
     // Append custom settings with missing params from default settings
     $container['settings']['logger'] = self::mergeWithDefaultSettings($container['settings']['logger']);
     /**
      * Add dependency (DI).
      *
      * @param Container $c
      *
      * @return Logger
      */
     $container['logger'] = function (Container $c) {
         $settings = $c['settings']['logger'];
         $loggerFormat = "[%datetime%] %level_name% %message% %context% %extra%\n";
         $loggerTimeFormat = "Y-m-d H:i:s";
         $loggerTimeZone = new DateTimeZone('Europe/Berlin');
         $logger = new Logger($settings['name']);
         if ($settings['color']) {
             $logger->pushProcessor(new ConsoleColorProcessor());
         }
         $logger->pushProcessor(new CleanupProcessor($settings['trimPaths']));
         $logger->pushProcessor(new IntrospectionProcessor(Logger::WARNING));
         $logger->pushProcessor(new ProcessIdProcessor());
         $logger->pushProcessor(new PsrLogMessageProcessor());
         $logger->setTimezone($loggerTimeZone);
         $logger->useMicrosecondTimestamps(false);
         // Using microseconds is buggy (2016-08-04)
         $formatter = new LineFormatter($loggerFormat, $loggerTimeFormat);
         $formatter->ignoreEmptyContextAndExtra(true);
         $defaultHandler = new StreamHandler('php://stdout', $settings['level'], $bubble = false);
         $defaultHandler->setFormatter($formatter);
         $logger->pushHandler($defaultHandler);
         $errorHandler = new StreamHandler('php://stderr', Logger::ERROR, $bubble = false);
         $errorHandler->setFormatter($formatter);
         $logger->pushHandler($errorHandler);
         // Register logger as default PHP error, exception and shutdown handler
         // Note: Make sure only this handler handles errors (set $callPrevious to false)
         $errorHandler = ErrorHandler::register($logger, $errorLevelMap = false, $exceptionLevelMap = false);
         $errorHandler->registerErrorHandler($levelMap = [], $callPrevious = false);
         $errorHandler->registerExceptionHandler($levelMap = [], $callPrevious = false);
         return $logger;
     };
 }