You can modify the container here before it is dumped to PHP code.

@param ContainerBuilder $container

@api
4576
public function process(ContainerBuilder $container)
    {
        $twig = $container->getDefinition('twig');

        $languages = array('en', 'fr');
        if ($container->hasParameter('open_orchestra_base.administration_languages')) {
            $languages = $container->getParameter('open_orchestra_base.administration_languages');
        }

        $twig->addMethodCall('addGlobal', array('administration_languages', $languages));
    }
588382
public function process(ContainerBuilder $container): void
    {
        $container->setParameter('service_bus.logger.echo.log_level', $this->logLevel);

        $container->addDefinitions(
            [
                StdOutHandler::class => (new Definition(StdOutHandler::class))->setArguments(['%service_bus.logger.echo.log_level%']),
            ]
        );

        (new LoggerCompilerPass())->process($container);

        $loggerDefinition = $container->getDefinition('service_bus.logger');

        $loggerDefinition->addMethodCall(
            'pushHandler',
            [new Reference(StdOutHandler::class)]
        );
    }
294609
public function loadServices(ContainerBuilder $container)
    {
        $loader = new XmlFileLoader($container, new FileLocator(__DIR__ . '/config'));
        $loader->load('services.xml');
        $this->imageDrivers = $this->driverLocator->findDrivers(
            $container,
            $this->imageDriverKeys,
            $this->imageDriverConfigs
        );
    }
26343
public function build(ContainerBuilder $container)
    {
        $container->addCompilerPass(new CommandProcessorPass(), PassConfig::TYPE_BEFORE_REMOVING);
        $container->addCompilerPass(new PoolsPass());
        $container->addCompilerPass(new RegisterSerializerDriversPass());
        $container->addCompilerPass(new WorkerRunnersPass());
    }
604930
public function prepend(ContainerBuilder $container)
    {
        $container->prependExtensionConfig('framework', [
            'translator' => [
                'paths' => [
                    dirname(dirname((new \ReflectionClass(LazyChainProvider::class))->getFileName())).'/Resources/translations',
                ],
            ],
        ]);
    }
653685
public function prepend(ContainerBuilder $container)
    {
        $configs = $container->getExtensionConfig($this->getAlias());
        $config = $this->processConfiguration(new Configuration(), $configs);

        $bundles = $container->getParameter('kernel.bundles');

        // Publish assetic assets if desired
        if ($config['assets']['publish'] && isset($bundles['AsseticBundle'])) {
            $container->prependExtensionConfig('assetic', array('assets' => $this->getAssets($config)));
        }
    }
952248
public function inject(ContainerBuilder $container)
    {
        foreach ($this->schema as $parameter) {

            $value = $parameter['default'];

            if ($this->parametersStorage->has($parameter['key'])) {
                $value = $this->parametersStorage->get($parameter['key']);
            }

            $container->setParameter($this->getParametersName($parameter['key']), $this->protectParameterValue($value));
        }
    }
1277211
public function process(ContainerBuilder $container)
    {
        $taggedServices = $container->findTaggedServiceIds(
            self::TAG_NAME
        );

        foreach ($taggedServices as $id => $tag) {
            $definition = $container->findDefinition($id);

            $this->processTag($tag, $definition);
        }
    }
564014
public function build(ContainerBuilder $container)
    {
        parent::build($container);

        $container->addCompilerPass(new MetaTagHandlersCompilerPass());
        $container->addCompilerPass(new TwigRuntimePass());
    }
1052498
public function prepend(ContainerBuilder $container)
    {
        $prependConfig = $this->getExtendedConfig($container);

        if (!empty($prependConfig)) {
            $container->prependExtensionConfig($this->getAlias(), $prependConfig);
        }
    }
404700
public function process(ContainerBuilder $container)
    {
        if (!$container->hasDefinition('drupal.event_dispatcher')) {
            return;
        }
        $dispatcherDefinition = $container->getDefinition('drupal.event_dispatcher');

        foreach ($container->findTaggedServiceIds('drupal.event_subscriber') as $id => $attributes) {
            foreach ($attributes as $attribute) {
                $priority = isset($attribute['priority']) ? intval($attribute['priority']) : 0;
                $dispatcherDefinition->addMethodCall(
                    'addSubscriber',
                    array(new Reference($id), $priority)
                );
            }
        }
    }
243951
public function process(ContainerBuilder $container)
    {
        $builderDefinition = $container->getDefinition(ItemBuilder::class);
        $factories = $container->findTaggedServiceIds('expansion.menu.item.factory');

        foreach ($factories as $id => $tags) {
            $builderDefinition->addMethodCall(
                "addItemFactory",
                [new Reference($id)]
            );
        }
    }
1255770
public function build(ContainerBuilder $container): void
    {
        parent::build($container);

        $container->addCompilerPass(new AddMenuVotersPass());
        $container->addCompilerPass(new ReplaceMenuMatcherPass());
        $container->addCompilerPass(new ConfigureAmazonMetaPass());
    }
323321
public function process(ContainerBuilder $container)
    {
        $this->compiler = $container->getCompiler();
        $this->formatter = $this->compiler->getLoggingFormatter();
        $this->graph = $this->compiler->getServiceReferenceGraph();

        $container->setDefinitions($this->inlineArguments($container, $container->getDefinitions(), true));
    }
777066
public function process(ContainerBuilder $container)
    {
        if (!$container->hasDefinition($this->subjectService)) {
            return;
        }

        $subjects = $this->findTaggedServices($container, $this->subjectTag, SubjectInterface::class, 'support', false);

        $subjectDefinition = $container->getDefinition($this->subjectService);
        $subjectDefinition->replaceArgument(0, $subjects);
    }
461173
public function process(ContainerBuilder $container)
    {
        if (!$container->has($this->getCollectorServiceName())) {
            return;
        }

        $definition = $container->findDefinition(
            $this->getCollectorServiceName()
        );

        $taggedServices = $this->findAndSortTaggedServices(
            $this->getTagName(),
            $container
        );

        /*
         * Per each service, add a new method call reference
         */
        foreach ($taggedServices as $service) {
            $definition->addMethodCall(
                $this->getCollectorMethodName(),
                [$service]
            );
        }
    }
165439
public function process(ContainerBuilder $container)
    {
        if (class_exists(BaseTranslator::class) && $container->hasDefinition('translator.default')
            && $container->hasParameter('translator.class')) {
            $class = $container->getParameter('translator.class');
            $definition = $container->getDefinition('translator.default');
            $definition->setClass($class);
        }
    }