client.go
func (r *FileResponse) FileName() string {
	value := r.headers.Get("Content-Disposition")
	if len(value) == 0 {
		return ""
	}
	_, params, err := mime.ParseMediaType(value)
	if err != nil {
		return ""
	}
	return params["filename"]
}
func (r *FileResponse) FileName() string {
	value := r.headers.Get("Content-Disposition")
	if len(value) == 0 {
		return ""
	}
	_, params, err := mime.ParseMediaType(value)
	if err != nil {
		return ""
	}
	return params["filename"]
}
// FileName returns HTTP file name