Blackfire\Player\Guzzle\RequestFactory::create PHP Method

    public function create(Step $step, ValueBag $values = null, RequestInterface $request = null, ResponseInterface $response = null, Crawler $crawler = null)
    {
        if (null === $values) {
            $values = new ValueBag();
        }
        if ($step->getUri()) {
            $request = $this->createRequestFromUri($step, $values);
        } elseif ($step->getLinkSelector()) {
            $request = $this->createRequestFromLink($step, $values, $crawler);
        } elseif ($step->getFormSelector()) {
            $request = $this->createRequestFromForm($step, $values, $crawler);
        } elseif ($step->isFollow()) {
            $request = $this->createRequestFromFollow($step, $values, $request, $response, $crawler);
        } else {
            throw new LogicException('A step needs a URI, a link, a form, or a follow redirect.');
        }
        return $request->withHeader('X-Request-Id', substr(sha1($request->getUri()), 0, 7));
    }