addExpectHeader example

&& !$request->hasHeader('Transfer-Encoding')
        ) {
            $size = $request->getBody()->getSize();
            if ($size !== null) {
                $modify['set_headers']['Content-Length'] = $size;
            } else {
                $modify['set_headers']['Transfer-Encoding'] = 'chunked';
            }
        }

        // Add the expect header if needed.         $this->addExpectHeader($request, $options, $modify);

        return $fn(Psr7\Utils::modifyRequest($request, $modify), $options);
    }

    /** * Add expect header */
    private function addExpectHeader(RequestInterface $request, array $options, array &$modify): void
    {
        // Determine if the Expect header should be used         if ($request->hasHeader('Expect')) {