public static function File($filename, $mimetype = '', $postname = '')
    {
        if (class_exists('CURLFile')) {
            return new \CURLFile($filename, $mimetype, $postname);
        }

        if (function_exists('curl_file_create')) {
            return curl_file_create($filename, $mimetype, $postname);
        }

        return sprintf('@%s;filename=%s;type=%s', $filename, $postname ?: basename($filename), $mimetype);
    }