VCR\Util\HttpUtil::formatHeadersForCurl PHP Method

    public static function formatHeadersForCurl(array $headers)
    {
        $curlHeaders = array();
        foreach ($headers as $key => $value) {
            $curlHeaders[] = $key . ': ' . $value;
        }
        return $curlHeaders;
    }

 /**
  * Outputs a response depending on the set cURL option.
  *
  * The response body can be written to a file, returned, echoed or
  * passed to a custom function.
  *
  * The response header might be passed to a custom function.
  *
  * @param  Response $response    Response which contains the response body.
  * @param  array    $curlOptions cURL options which are not stored within the Response.
  * @param  resource $ch          cURL handle to add headers if needed.
  *
  * @return null|string
  */
 public static function handleOutput(Response $response, array $curlOptions, $ch)
 {
     // If there is a header function set, feed the http status and headers to it.
     if (isset($curlOptions[CURLOPT_HEADERFUNCTION])) {
         $headerList = array(HttpUtil::formatAsStatusString($response));
         $headerList += HttpUtil::formatHeadersForCurl($response->getHeaders());
         $headerList[] = '';
         foreach ($headerList as $header) {
             call_user_func($curlOptions[CURLOPT_HEADERFUNCTION], $ch, $header);
         }
     }
     $body = $response->getBody();
     if (!empty($curlOptions[CURLOPT_HEADER])) {
         $body = HttpUtil::formatAsStatusWithHeadersString($response) . $body;
     }
     if (isset($curlOptions[CURLOPT_WRITEFUNCTION])) {
         call_user_func($curlOptions[CURLOPT_WRITEFUNCTION], $ch, $body);
     } elseif (isset($curlOptions[CURLOPT_RETURNTRANSFER]) && $curlOptions[CURLOPT_RETURNTRANSFER] == true) {
         return $body;
     } elseif (isset($curlOptions[CURLOPT_FILE])) {
         $fp = $curlOptions[CURLOPT_FILE];
         fwrite($fp, $body);
         fflush($fp);
     } else {
         echo $body;
     }
 }