PicoFeed\Client\Curl::prepareHeaders PHP Method

    private function prepareHeaders()
    {
        $headers = array('Connection: close');
        if ($this->etag) {
            $headers[] = 'If-None-Match: ' . $this->etag;
            $headers[] = 'A-IM: feed';
        }
        if ($this->last_modified) {
            $headers[] = 'If-Modified-Since: ' . $this->last_modified;
        }
        $headers = array_merge($headers, $this->request_headers);
        return $headers;
    }