/**
  * outputs the response
  *
  * @param ResponseInterface $response
  */
 private function writeResponse(ResponseInterface $response)
 {
     if (!$response->hasHeader("content-type")) {
         $response = $response->withHeader("Content-Type", "text/html");
     }
     if (!headers_sent()) {
         header(sprintf("HTTP/%s %s %s", $response->getProtocolVersion(), $response->getStatusCode(), $response->getReasonPhrase()), true, $response->getStatusCode());
         foreach ($response->getHeaders() as $name => $values) {
             header(sprintf("%s: %s", $name, implode(",", $values)));
         }
     }
     $bodyStream = $response->getBody();
     $bodyStream->rewind();
     echo $bodyStream->getContents();
 }