Bagaimana Mengendalikan Penyerahan Borang Berbilang Bahagian dalam Go menggunakan `mime/multipart` dan `http`?

<form action="/multipart" enctype="multipart/form-data" method="POST">
  <label for="file">Please select a File </label>
  <input>

var buffer bytes.Buffer
w := multipart.NewWriter(&buffer)
// Write fields and files
w.CreateFormField("input1")
w.WriteField("input1", "value1")
w.CreateFormFile("file", "filename.dat")
// Create a reader to read the file
resp, err := http.Post(url, w.FormDataContentType(), &buffer)

// Upload file to google code
func Upload(tarball string) (err os.Error) {
    // ... (code omitted)
    // Create file field
    fw, err := w.CreateFormFile("upload", tarball)
    // ... (code omitted)
    // Write file field from file to upload
    _, err = io.Copy(fw, fd)
    // ... (code omitted)
    return err
}