drewm / mailchimp-api

     * @param RequestInterface $request

     * @return string

     */

    private function getRequestHeader(RequestInterface $request): string

    {

        $requestHeader = sprintf(

            "%s %s HTTP/%s\r\n",

            $request->getMethod(),

            $request->getRequestTarget(),

            $request->getProtocolVersion()

        );

        foreach ($request->getHeaders() as $headerName => $headerValues) {

            $requestHeader .= sprintf("%s: %s\r\n", $headerName, implode(', ', $headerValues));

        }

        $requestHeader .= "\r\n";

        return $requestHeader;

    }

    /**

     * @param ResponseInterface $request

     * @param ResponseInterface $request

     * @return string

     */

    private function getResponseHeader(ResponseInterface $response): string

    {

        $responseHeader = sprintf(

            "HTTP/%s %s %s\r\n",

            $response->getProtocolVersion(),

            $response->getStatusCode(),

            $response->getReasonPhrase()

        );

        foreach ($response->getHeaders() as $headerName => $headerValues) {

            $responseHeader .= sprintf("%s: %s\r\n", $headerName, implode(', ', $headerValues));

        }

        $responseHeader .= "\r\n";

        return $responseHeader;

    }

    /**

     * @param string  $http_verb