请问如何监听GuzzleHttp的请求？

public function request(string $url, string $method, Closure $callback): ApiResponse
    {
        $this->url = $url;
        $this->method = strtoupper($method);
        // 执行中间件
        $middlewares = $this->getMiddleware();
        $pipeline = app(Pipeline::class);
        $response = $pipeline->send($this)
            ->through($middlewares)
            ->then(function () use ($callback) {
                event(new ApiRequestStart($this));
                // 记录请求开始时间
                $this->start();
                // 请求接口
                $response = $this->fetch($this->getUrl(), $this->getMethod());
                // 记录请求结束时间
                $this->end();
                try {
                    // 处理请求后的接口, 该闭包一般用来格式化接口数据和判断接口返回是否正常
                    $response = $callback($response);
                } catch (Throwable $e) {
                    // 记录错误日志, 不在这抛出异常(因日志中间件会走不下去). 当全部中间件执行完后才由后面抛出
                    $response->setError()->setErrorCode($e->getCode())->setMessage($e->getMessage())->setException($e);
                } finally {
                    // 触发请求完成事件
                    event(new ApiRequestComplete($this, $response));
                }
                return $response;
            });

        // 有异常时直接抛出指定异常
        if ($response->getException()) {
            throw $response->getException();
        }

        // 其他出错时抛出(正常情况是不会走进这里的, 一般会在上面的$callback($response)把异常全部抛出来)
        if ($response->isError()) {
            throw new RequestException($response->getMessage(), $response->getErrorCode());
        }

        return $response;
    }Copy

use GuzzleHttp\Client;
use GuzzleHttp\HandlerStack;
use GuzzleHttp\Middleware;
use GuzzleHttp\Utils;
use Psr\Http\Message\RequestInterface;

$stack = new HandlerStack();
$stack->setHandler(Utils::chooseHandler());

$stack->push(Middleware::mapRequest(function (RequestInterface $r) {
    echo 'A';
    return $r;
}));

$stack->push(Middleware::mapRequest(function (RequestInterface $r) {
    echo 'B';
    return $r;
}));

$stack->push(Middleware::mapRequest(function (RequestInterface $r) {
    echo 'C';
    return $r;
}));

$client->request('GET', 'http://httpbin.org/');
// echoes 'ABC';

$stack->unshift(Middleware::mapRequest(function (RequestInterface $r) {
    echo '0';
    return $r;
}));

$client = new Client(['handler' => $stack]);
$client->request('GET', 'http://httpbin.org/');
// echoes '0ABC';Copy