if err != nil {
			log.Fatal(err)
		}
		if strings.HasSuffix(path, ".zip") {
			log.Fatalf("unexpected file during walk: %s", path)
		}
		name := filepath.ToSlash(path)
		w, err := zw.CreateRaw(&zip.FileHeader{
			Name:               name,
			Method:             zip.Store,
			CompressedSize64:   uint64(len(data)),
			UncompressedSize64: uint64(len(data)),
			CRC32:              crc32.ChecksumIEEE(data),
		})

pkg archive/zip, method (*File) OpenRaw() (io.Reader, error)
pkg archive/zip, method (*Writer) Copy(*File) error
pkg archive/zip, method (*Writer) CreateRaw(*FileHeader) (io.Writer, error)
pkg compress/lzw, method (*Reader) Close() error
pkg compress/lzw, method (*Reader) Read([]uint8) (int, error)
pkg compress/lzw, method (*Reader) Reset(io.Reader, Order, int)
pkg compress/lzw, method (*Writer) Close() error

pkg mime/multipart, method (*Writer) CreateFormField(string) (io.Writer, error)
pkg mime/multipart, method (*Writer) CreateFormFile(string, string) (io.Writer, error)
pkg mime/multipart, method (*Writer) CreatePart(textproto.MIMEHeader) (io.Writer, error)
pkg mime/multipart, method (*Writer) FormDataContentType() string
pkg mime/multipart, method (*Writer) WriteField(string, string) error