PHP Fatal error: Uncaught Error: Class 'Amp\Log\StreamHandler' not found in

I am unable to run the sample in the documentation because the logger is not working using the command and the code below.

Install as composer dependency

$composer require amphp/http-server --dev

Run Code

$php test.php

<?php
use Amp\ByteStream;
use Amp\Http\HttpStatus;
use Amp\Http\Server\DefaultErrorHandler;
use Amp\Http\Server\Request;
use Amp\Http\Server\RequestHandler;
use Amp\Http\Server\Response;
use Amp\Http\Server\SocketHttpServer;
use Amp\Log\ConsoleFormatter;
use Amp\Log\StreamHandler;
use Monolog\Logger;
use Monolog\Processor\PsrLogMessageProcessor;

require __DIR__.'/vendor/autoload.php';

// Note any PSR-3 logger may be used, Monolog is only an example.
$logHandler = new StreamHandler(ByteStream\getStdout());
$logHandler->pushProcessor(new PsrLogMessageProcessor());
$logHandler->setFormatter(new ConsoleFormatter());

$logger = new Logger('server');
$logger->pushHandler($logHandler);

$requestHandler = new class() implements RequestHandler {
    public function handleRequest(Request $request) : Response
    {
        return new Response(
            status: HttpStatus::OK,
            headers: ['Content-Type' => 'text/plain'],
            body: 'Hello, world!',
        );
    }
};

$errorHandler = new DefaultErrorHandler();

$server = SocketHttpServer::createForDirectAccess($logger);
$server->expose('127.0.0.1:1337');
$server->start($requestHandler, $errorHandler);

// Serve requests until SIGINT or SIGTERM is received by the process.
Amp\trapSignal([SIGINT, SIGTERM]);

$server->stop();

Im getting the error

PHP Fatal error:  Uncaught Error: Class 'Amp\Log\StreamHandler' not found in 

Start with the documentation sample, its Composer install command, and the Amp\Log\StreamHandler import shown in the report. Reproduce the failure with php test.php after installing the documented dependency, then verify that the sample runs without the reported fatal error.