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
pkg mime/multipart, type File interface { Close, Read, ReadAt, Seek }
pkg mime/multipart, type File interface, Close() error
pkg mime/multipart, type File interface, Read([]uint8) (int, error)