Bolt\Provider\GuzzleServiceProvider::register PHP Method

    public function register(Application $app)
    {
        $app['guzzle.base_url'] = '/';
        $app['guzzle.api_version'] = $app->share(function () use($app) {
            return version_compare(Client::VERSION, '6.0.0', '>=') ? 6 : 5;
        });
        if (!isset($app['guzzle.handler_stack'])) {
            $app['guzzle.handler_stack'] = $app->share(function () {
                return HandlerStack::create();
            });
        }
        // Register a simple Guzzle Client object (requires absolute URLs when guzzle.base_url is unset)
        $app['guzzle.client'] = $app->share(function () use($app) {
            $options = ['base_uri' => $app['guzzle.base_url'], 'handler' => $app['guzzle.handler_stack']];
            $client = new Client($options);
            return $client;
        });
    }